A Level Psychology and the Difficult Question of Abnormality: Could a Sane Person Prove They Were Sane?

 

Rosenhan (1973): Could a Sane Person Prove They Were Sane?

A Level Psychology and the Difficult Question of Abnormality

Imagine entering a psychiatric hospital knowing that there is nothing mentally wrong with you.

You have reported hearing a voice, but after admission you behave normally. You speak sensibly, cooperate with the staff, explain that the voice has disappeared and quietly record what happens around you.

How long would it take before someone recognised that you were not mentally ill?

A few hours?

Perhaps a day?

Surely an experienced psychiatrist would soon realise that a mistake had been made.

David Rosenhan’s famous 1973 study, On Being Sane in Insane Places, suggested that the answer might be much more worrying. His research raised the possibility that once a person had been given a psychiatric label, almost everything they did could be interpreted through that label.

However, Rosenhan’s study raises an even larger question:

What do we actually mean by mental abnormality?

Is abnormality something statistically unusual? Is it behaviour that breaks society’s rules? Is it an inability to manage everyday life? Or is it simply a failure to meet an ideal picture of mental wellbeing?

These are not merely examination questions. The answers can affect whether a person receives treatment, loses their independence, experiences stigma or is taken seriously when asking for help.

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Why Did Rosenhan Conduct the Study?

Rosenhan was interested in the validity of psychiatric diagnosis.

Validity concerns whether a diagnosis is accurate: does the label genuinely identify the condition it claims to identify?

He was also interested in reliability. Would different clinicians looking at the same person reach similar conclusions?

Physical illnesses can often be investigated using blood tests, scans, biopsies and other measurements. Mental health diagnoses depend much more heavily on interviews, descriptions of experiences, observed behaviour and professional judgement.

That does not mean mental illness is not real. Depression, psychosis, anxiety and other forms of psychological suffering can be severe and disabling.

The problem is deciding how clinicians distinguish between:

• an unusual experience and a psychiatric symptom;

• temporary distress and a lasting disorder;

• eccentric behaviour and harmful dysfunction;

• culturally acceptable behaviour and behaviour considered abnormal;

• someone who is mentally unwell and someone who only appears to be.

Rosenhan wanted to discover whether trained professionals could reliably distinguish a person who was experiencing mental illness from someone who was not.

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The First Part of the Study: Eight “Pseudopatients”

Rosenhan organised a form of covert participant observation.

Eight mentally healthy people, including Rosenhan himself, attempted to gain admission to 12 psychiatric hospitals in the United States. Rosenhan called them pseudopatients.

The hospitals varied considerably. They included public and private institutions, hospitals with different levels of funding and facilities located in different parts of the country.

Each pseudopatient contacted a hospital and reported hearing a voice. The voice was described as unclear but appeared to say words such as “empty”, “hollow” or “thud”.

Apart from this reported hallucination and changes to identifying information, the pseudopatients were instructed to tell the truth about their lives.

All eight were admitted. Seven received a diagnosis of schizophrenia, while one was diagnosed with manic-depressive psychosis, the historical terminology used at the time. After admission, they stopped reporting symptoms and behaved normally. Their hospital stays lasted from 7 to 52 days, with an average of 19 days. None was identified by hospital staff as a pseudopatient.

This result is often presented very simply:

Eight sane people entered psychiatric hospitals and the psychiatrists failed to recognise that they were sane.

However, the situation is more complicated than that.

The pseudopatients had deliberately reported a symptom associated with serious mental illness. A clinician assessing someone who claims to hear voices cannot simply assume that the person is lying. Admitting a patient for further observation could be viewed as a cautious response rather than obvious incompetence.

The more troubling part of the study was what happened after the pseudopatients began behaving normally.

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Once the Label Was Applied, Everything Looked Like a Symptom

The pseudopatients openly wrote notes about their experiences.

Rather than treating this as normal note-taking, staff sometimes interpreted it as part of the supposed illness. One record referred to “writing behaviour”, as though the act of writing itself had become clinically significant.

Ordinary details from the pseudopatients’ lives were also interpreted in ways that appeared to support the diagnosis.

This demonstrates the possible effect of confirmation bias.

Confirmation bias occurs when people pay greater attention to information that supports an existing belief while overlooking evidence that challenges it.

Once the staff believed that a person had schizophrenia, normal behaviour could be reinterpreted as evidence of schizophrenia:

• Writing notes became “writing behaviour”.

• Waiting for lunch could be interpreted as an abnormal preoccupation with food.

• Asking when they would be released could appear demanding or symptomatic.

• Nervousness could be seen as evidence of illness rather than a reasonable reaction to being confined in a psychiatric hospital.

• Calm behaviour might be interpreted as a temporary improvement rather than evidence that the original diagnosis was wrong.

The label did not simply describe the person. It influenced how other people perceived the person.

That is one reason Rosenhan remains useful when teaching labelling theory, institutionalisation, observer bias and the social construction of abnormality.

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The Patients Sometimes Saw What the Professionals Missed

Another striking feature was that some of the genuine patients suspected that the pseudopatients were not mentally ill.

Some suggested that they might be journalists or researchers investigating the hospital.

This presents an uncomfortable contrast. Patients who lacked professional qualifications sometimes appeared more willing than staff to question the original label.

One possible explanation is that patients spent more time with one another. They saw each other across a wide range of situations rather than through brief formal interviews or medical records.

Staff members were also working within an institution. They had procedures to follow, limited time and responsibilities for many patients. Their observations were shaped by the hospital environment and by the information already written in the patient’s notes.

This does not necessarily mean that individual staff members were uncaring or incompetent. It suggests that the system itself may have encouraged particular interpretations.

That is an important lesson for psychology students: behaviour does not occur in isolation. We need to consider both the person and the situation.

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Could the Pseudopatients Simply Announce the Truth?

One might imagine that the pseudopatients could have said:

“I am not mentally ill. This is an experiment.”

The difficulty is that this statement might itself have been dismissed.

Once someone has been classified as mentally ill, protesting against the diagnosis may be interpreted as a lack of insight into their condition. The attempt to disprove the label can therefore be used to reinforce it.

This creates a disturbing circular argument:

1. The person is diagnosed as mentally ill.

2. The person denies being mentally ill.

3. The denial is interpreted as evidence that the person lacks insight.

4. The diagnosis is therefore maintained.

The pseudopatients were eventually discharged, but most left with a diagnosis of schizophrenia “in remission” rather than with the admission that no disorder had been present.

In other words, the label was modified but not completely removed.

This illustrates the potential stickiness of psychiatric labels. Once applied, they can influence future expectations, treatment decisions and how behaviour is interpreted.

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The Second Part: Looking for Pseudopatients Who Did Not Exist

The second part of Rosenhan’s research reversed the problem.

A research and teaching hospital had reportedly argued that errors like those in the first phase would not happen there. Staff were told that Rosenhan might send one or more pseudopatients during the following months.

Staff therefore assessed incoming patients and judged whether they might be impostors.

Among 193 patients, 41 were judged highly likely to be pseudopatients by at least one staff member. Twenty-three were suspected by at least one psychiatrist, and 19 were suspected by both a psychiatrist and at least one other staff member.

Rosenhan had sent no pseudopatients.

It would be misleading to say simply that “mentally ill people were declared sane”. The staff were not necessarily declaring that these people had no difficulties. They were judging that some might be pretending to have symptoms.

Nevertheless, the result demonstrated the power of expectation.

During the first phase, staff expected to see mental illness and therefore saw evidence of illness in normal behaviour.

During the second phase, staff expected to encounter impostors and therefore became suspicious of genuine patients.

The direction of the error changed because the expectation changed.

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False Positives and False Negatives

The study can be understood through two types of diagnostic error.

A false positive

A false positive occurs when a person who does not have a disorder is diagnosed as having one.

The pseudopatients in the first phase represented alleged false positives.

A false negative

A false negative occurs when a genuine condition is missed or dismissed.

The second phase created the risk that genuine patients might be treated as impostors.

Neither error is harmless.

A false positive may expose someone to:

• inappropriate medication;

• unnecessary hospital admission;

• stigma;

• loss of independence;

• disruption to education, employment and family life;

• a medical record that influences future decisions.

A false negative may mean that someone who desperately needs help is not believed or treated.

Psychological diagnosis must therefore balance two serious risks: diagnosing a disorder that is not present and failing to recognise one that is.

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What Is Mental Abnormality?

Modern A Level Psychology courses commonly examine four definitions in the field of mental health:

1. deviation from ideal mental health;

2. deviation from social or cultural norms;

3. failure to function adequately;

4. statistical infrequency.

Each definition captures something useful, but none provides a complete answer.

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1. Statistical Infrequency

Under this definition, a behaviour or characteristic may be considered abnormal when it is statistically rare.

For example, an extremely low IQ score is unusual within the population and may be associated with an intellectual disability when accompanied by difficulties in adaptive functioning.

This approach appears objective because it uses numerical data.

However, rarity does not automatically mean illness.

An exceptionally high IQ is statistically unusual but is not normally regarded as a disorder. Exceptional musical ability, extraordinary memory and elite athletic performance are also rare.

The opposite problem occurs when an undesirable experience is common. Anxiety, stress and periods of low mood may affect large numbers of people. Their frequency does not make severe suffering unimportant.

Statistical infrequency can tell us that someone is unusual. It cannot, by itself, tell us that the person is unwell.

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2. Deviation from Social or Cultural Norms

Every society has expectations about acceptable behaviour.

These include formal rules, such as laws, and informal expectations concerning clothing, communication, personal space, relationships and emotional expression.

A person who seriously violates these expectations may be judged abnormal.

The problem is that social norms are not fixed.

They vary:

• between cultures;

• between generations;

• between social groups;

• according to the situation;

• across historical periods.

Talking loudly to oneself might attract concern in a library but seem entirely normal during a theatre rehearsal. Removing one’s clothes would usually be unacceptable in a supermarket but expected in a changing room.

Even the same behaviour can be judged differently depending on who performs it.

Social norms can also be used to control people who challenge authority. Political protest, religious practice, sexuality and gender expression have all been judged differently across cultures and historical periods.

Deviation from a social norm may tell us that society disapproves of a behaviour. It does not automatically prove the presence of mental illness.

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3. Failure to Function Adequately

This definition focuses on whether a person can manage everyday life.

Possible indicators include difficulty:

• caring for oneself;

• maintaining relationships;

• attending school or work;

• communicating effectively;

• managing personal safety;

• coping with ordinary responsibilities;

• experiencing life without overwhelming distress.

This approach can be more humane because it considers the effect of a condition on the individual rather than merely asking whether the behaviour looks unusual.

For example, repeatedly checking that a door is locked might appear relatively harmless. If the checking takes several hours, causes extreme anxiety and prevents the person from leaving home, it has become seriously maladaptive.

However, functioning is also difficult to judge.

Some people continue working and caring for others while experiencing severe psychological distress. Outward achievement does not necessarily mean that someone is well.

Conversely, a person may temporarily struggle to function after bereavement, illness, unemployment or another major life event. That does not automatically mean that they have a psychiatric disorder.

There is also the question of who decides what “adequate” functioning looks like.

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4. Deviation from Ideal Mental Health

Instead of defining illness, this approach begins by describing positive psychological wellbeing.

Marie Jahoda suggested that ideal mental health might involve characteristics such as:

• a positive attitude towards oneself;

• personal growth and self-actualisation;

• independence;

• resistance to stress;

• an accurate perception of reality;

• successful adaptation to the environment.

Someone who falls substantially below these ideals might be considered psychologically abnormal.

This definition has a positive focus. It encourages us to think of mental health as more than the absence of a diagnosed disorder.

However, the criteria may be too demanding.

Most people occasionally doubt themselves, misunderstand situations, depend on other people or fail to cope well with stress. If perfect psychological health is the standard, almost everyone becomes abnormal.

Some criteria may also reflect Western ideas about independence, personal achievement and self-development. Other cultures may place greater value on family duty, interdependence and community.

The definition offers a useful goal, but it may not provide a fair diagnostic boundary.

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What Rosenhan Shows About These Definitions

Rosenhan’s pseudopatients were statistically ordinary in many respects, functioned effectively outside the hospitals and did not display continuing symptoms after admission.

Nevertheless, they had reported an experience that was both unusual and associated with deviation from ordinary expectations: hearing a voice that other people could not hear.

That single reported symptom was enough to place them within a powerful diagnostic context.

The study suggests that definitions of abnormality are not applied mechanically. Human judgement remains involved.

Clinicians must decide:

• how unusual a behaviour is;

• whether it is culturally appropriate;

• whether it causes distress;

• whether it affects functioning;

• how long it has lasted;

• whether another explanation is more likely;

• how much risk is involved;

• whether the person’s account is reliable.

The diagnosis is therefore influenced not only by behaviour but also by context, interpretation and expectations.

---

A Useful Classroom Activity: How Much Does a Label Change Our Judgement?

One effective way to explore Rosenhan is to give two groups of students an identical description of a person.

For example:

Alex has recently moved to a new city. Alex spends a great deal of time alone, keeps the curtains closed, writes extensively in notebooks and sometimes smiles without an obvious reason.

Tell the first group that Alex is a university student preparing a novel.

Tell the second group that Alex has recently been discharged from a psychiatric hospital.

Then ask both groups to explain the behaviour.

The first group may decide that Alex is creative, private and absorbed in writing.

The second may interpret the closed curtains as withdrawal, the notebooks as obsessive behaviour and the smiling as evidence of responding to an unseen stimulus.

The behaviour has not changed.

Only the label has changed.

This does not prove that diagnosis is always wrong. It demonstrates how prior information can alter interpretation.

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Another Activity: Does Context Change Abnormality?

Students can examine the same behaviour in different settings:

Speaking to someone who is not visibly present

• In 1973, this might have appeared highly unusual.

• Today, the person may be using a small wireless headset.

• In a religious setting, the person might be praying.

• In a drama lesson, the person may be rehearsing.

• In another case, the person may genuinely be experiencing an auditory hallucination.

The observable behaviour is similar, but its meaning changes with context.

Students should therefore learn to ask:

What else would I need to know before reaching a conclusion?

That is a much more scientific response than immediately applying a label.

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Evaluating Rosenhan’s Study

Strength: High Ecological Validity

The research took place in real psychiatric hospitals.

The pseudopatients encountered genuine admission procedures, clinicians, institutional rules and ward environments. This gives the study a realism that would be difficult to reproduce in a laboratory.

The consequences were also real. Participants experienced admission, diagnosis and the difficulty of securing discharge.

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Strength: It Revealed the Possible Power of Labels

Rosenhan demonstrated how a diagnostic label might influence the interpretation of later behaviour.

This has applications beyond psychiatry.

Teachers, employers, doctors and even family members can begin to interpret everything through an existing label:

• “lazy”;

• “gifted”;

• “troublesome”;

• “anxious”;

• “aggressive”;

• “attention-seeking”.

Once attached, a label can become a lens through which all later behaviour is viewed.

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Strength: It Generated an Important Debate

The study forced psychology and psychiatry to confront questions about reliability, validity, institutional treatment and the dignity of patients.

Later diagnostic manuals introduced more explicit, operationalised criteria intended to improve consistency. Research suggests that structured criteria improved reliability in some research settings, although disagreement and uncertainty were not eliminated.

The wider lesson is that criticism can improve a discipline when it leads to better methods rather than simple rejection.

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Limitation: The Pseudopatients Did Report a Serious Symptom

The pseudopatients were not simply healthy people who walked into hospitals while behaving normally.

They reported hearing voices.

From a clinician’s perspective, this could justify further assessment, particularly when failing to admit someone experiencing psychosis might place that person at risk.

Psychiatrist Robert Spitzer argued that Rosenhan’s conclusions went beyond what the research demonstrated. Failure to detect someone who is deliberately presenting a convincing symptom is not necessarily the same as being unable to recognise sanity.

This is a valuable evaluation point because it prevents students from accepting a dramatic conclusion without questioning the method.

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Limitation: The Sample Was Very Small

Only eight pseudopatients took part.

Although they attended different hospitals, this remains a limited sample from one country and one historical period.

Psychiatric hospitals, staff training, diagnostic manuals and attitudes towards patients have changed since the early 1970s.

We should be cautious about assuming that exactly the same results would occur in every modern mental health service.

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Limitation: Ethical Problems

The hospital staff did not give informed consent to participate in the study.

They were deceived and could not withdraw because they did not know that research was taking place.

Genuine patients were also observed without being asked for consent.

The pseudopatients themselves faced psychological and physical risks. They entered institutions without knowing how long they would remain or how they would be treated.

The research therefore created serious tensions between the value of the findings and the rights of participants.

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Limitation: The Research Is Difficult to Replicate

A precise replication would be ethically and practically difficult.

Modern researchers could not easily arrange for healthy participants to deceive psychiatric services, occupy hospital places and receive unnecessary treatment.

This makes it difficult to test the reliability of Rosenhan’s findings using the same procedure.

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A More Recent Controversy

Rosenhan’s study is often presented in textbooks as a clear and settled piece of evidence.

It is not.

Later investigations have questioned the completeness of Rosenhan’s records, the identities and experiences of the reported pseudopatients and whether the published account accurately represented everything that happened.

Contemporary commentators have therefore argued that the study should be taught critically rather than accepted as an unquestionable historical fact.

This does not make the questions raised by Rosenhan unimportant.

It means the study itself must be subjected to the same careful examination that it demanded of psychiatry.

That is how science should work.

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What Should A Level Students Conclude?

The weakest conclusion would be:

“Rosenhan proved that psychiatrists cannot identify mental illness.”

That is too broad.

A stronger conclusion would be:

“Rosenhan demonstrated how expectations, diagnostic labels and institutional contexts may influence the interpretation of behaviour.”

An even better conclusion would add:

“However, the pseudopatients deliberately reported a serious symptom, the sample was small, the procedure was ethically problematic and later researchers have questioned aspects of the original account.”

That type of answer demonstrates knowledge, application, analysis and evaluation.

It also avoids treating a complex study as a simple story in which the researchers were clever and the hospital staff were foolish.

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A Personal Reflection: This Study Should Create Humility, Not Cynicism

When I teach Rosenhan, students are often fascinated by the apparent absurdity of the situation.

They imagine that they would immediately recognise the pseudopatients. They are confident that they would not be influenced by a label.

The classroom activities usually weaken that confidence.

Once students receive information suggesting that a person has a disorder, they often begin to interpret ambiguous behaviour as evidence of that disorder. They are not deliberately being unfair. They are doing what human beings naturally do: using prior information to make sense of uncertainty.

That is why the most important lesson from Rosenhan is not that mental health professionals are untrustworthy.

It is that all human judgement is vulnerable to bias.

Expertise should reduce that risk, but expertise does not remove it completely.

Good diagnosis therefore requires:

• clear criteria;

• sufficient time;

• careful listening;

• evidence from more than one source;

• awareness of culture and context;

• consideration of alternative explanations;

• willingness to revise an earlier judgement;

• respect for the individual behind the label.

A diagnosis may help someone understand their experiences and access effective treatment. It should not become the person’s entire identity.

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Conclusion: Who Decides What Is Normal?

Rosenhan’s study remains disturbing because it challenges our confidence in a simple dividing line between sanity and insanity.

Mental health is not usually a switch that is either on or off. It is often a continuum involving distress, functioning, duration, context, risk and culture.

Statistical rarity is not enough.

Breaking a social norm is not enough.

Struggling to function is important but not always proof of a disorder.

Failing to achieve perfect mental health would classify almost everyone as abnormal.

No single definition solves the problem.

Rosenhan’s study should not be used to claim that mental illness is imaginary or that diagnosis has no value. Psychological suffering is real, and accurate diagnosis can lead to support, understanding and treatment.

The study offers a warning instead:

Never allow a label to become more important than the person being observed.

A scientific and humane mental health system must be capable of making careful judgements—but it must also be capable of questioning them.

Perhaps the most important sign of a reliable professional is not absolute certainty.

It is the willingness to ask:

“What evidence would make me reconsider my conclusion?”

 

Building an A Level Platform Game Project — Part 4: Adding Platforms and Collision Detection

In Part 1, we planned the platform game and set realistic success criteria.

In Part 2, we created the game window and added basic left and right movement.

In Part 3, we added gravity and jumping, so the player could rise, fall and land on the ground.

Now we reach one of the most important stages in the whole project: platforms and collision detection.

This is where the game stops being a character jumping on a single ground line and starts to become a proper platform game world.

It is also where many students discover that game programming is not quite as simple as it first appears.

A platform looks simple. It is just a rectangle on the screen.

But the program has to answer some awkward questions:

• Has the player landed on top of the platform?

• Has the player hit the side of the platform?

• Has the player jumped into the underside of the platform?

• Should the player stand on the platform or fall through it?

• What happens if the player is moving quickly?

• How does the program know which platform the player is touching?

This is why collision detection is such a good A Level Computer Science topic. It takes a simple visual idea and turns it into a proper programming problem.

Why Platforms Matter

A platform game needs a world for the player to interact with.

So far, our player can move, jump and land, but only on the bottom of the screen. That is useful for testing, but it is not enough for a game.

Platforms allow us to create:

• different routes through the level

• jumps of different difficulty

• collectables placed in interesting positions

• hazards that must be avoided

• areas that require planning and timing

• a proper start and finish point

Once platforms work, we can begin to design levels.

That is why this article is so important. Collision detection is the bridge between movement and level design.

The Aim for Part 4

The aim of this stage is:

Add rectangular platforms to the game and allow the player to land on them without falling through.

By the end of this stage, the game should include:

• several visible platforms

• a player affected by gravity

• collision detection between the player and platforms

• the ability to land on top of platforms

• prevention of repeated jumping while in the air

• testing evidence showing that platforms work correctly

This is still a prototype, but it is now much closer to a real game.

Representing Platforms

The simplest platform can be represented as a rectangle.

In Pygame-style code, a platform might be written as:

platform = pygame.Rect(200, 450, 200, 20)

This creates a rectangle with:

• x-position: 200

• y-position: 450

• width: 200

• height: 20

Instead of one platform, we can store several platforms in a list:

platforms = [
    pygame.Rect(0, 580, 800, 20),
    pygame.Rect(150, 480, 200, 20),
    pygame.Rect(450, 380, 200, 20),
    pygame.Rect(250, 280, 180, 20)
]

This gives us a basic level layout:

• a ground platform at the bottom

• one platform slightly higher

• another platform further across

• a higher platform above

This simple list is already important.

It means the level is not just drawn manually. It is stored as data.

That is a key idea for future articles, because later we can develop this into proper level design.

Drawing the Platforms

Once the platforms are stored in a list, they can be drawn using a loop:

for platform in platforms:
    pygame.draw.rect(screen, (0, 0, 0), platform)

This is better than writing a separate drawing command for every platform.

It also makes the project easier to extend.

If we want to add another platform, we add another rectangle to the list. The drawing loop does not need to change.

This is a good point for students to mention in their project documentation:

I stored the platforms in a list so that the program could process them using a loop. This made it easier to add, remove or change platforms without rewriting the drawing code.

That shows good programming thinking.

Representing the Player as a Rectangle

In earlier versions, the player used separate variables such as:

player_x
player_y
player_width
player_height

For collision detection, it is useful to create a rectangle for the player as well:

player_rect = pygame.Rect(player_x, player_y, player_width, player_height)

A rectangle makes it easier to check whether the player overlaps a platform.

For example:

if player_rect.colliderect(platform):
    print("Collision detected")

This is the basic idea behind rectangle collision detection.

It is not perfect, but it is ideal for a first platform game.

What Is Collision Detection?

Collision detection means checking whether two objects are touching or overlapping.

In this project, we need to know when the player touches:

• the ground

• a platform

• a wall

• a hazard

• a collectable

• a finish point

For now, we will focus only on platforms.

The simplest approach is rectangle collision detection.

If the player rectangle overlaps a platform rectangle, a collision has happened.

That sounds easy.

The difficult part is deciding what to do after the collision.

Why Collision Response Is Harder Than Collision Detection

Detecting a collision simply tells us that two rectangles overlap.

It does not automatically tell us where the collision happened.

The player might have:

• landed on top of the platform

• hit the platform from below

• run into the side

• touched a corner

The response should be different in each case.

If the player lands on top, they should stand on the platform.

If the player hits the underside, they should stop moving upwards.

If the player hits the side, they should not pass through the platform.

For this stage, we will keep things simple and focus on landing on top of platforms.

Side collisions can be developed later.

This is a sensible project decision because it controls the scope.

A Simple Landing Algorithm

To land on a platform, the program needs to check whether the player is falling and whether the bottom of the player has reached the top of the platform.

The player is falling when:

player_y_velocity > 0

The bottom of the player is:

player_rect.bottom

The top of the platform is:

platform.top

If the player is falling and collides with a platform, we can place the player on top of the platform:

player_rect.bottom = platform.top
player_y_velocity = 0
on_ground = True

This means:

• the player is no longer falling

• the player is positioned exactly on top of the platform

• the player is allowed to jump again

That is the basic idea.

Updating the Player Position

One important issue is that the player’s rectangle must be updated as the player moves.

A sensible structure is:

1. Check input.

2. Move horizontally.

3. Apply gravity.

4. Move vertically.

5. Check collisions with platforms.

6. Draw everything.

The order matters.

If the order is wrong, collisions may behave strangely.

For example, if the program checks collisions before the player moves, it may be using old position data.

Example Code for Platforms and Landing

Here is a simplified version of the Part 4 prototype:

import pygame

pygame.init()

SCREEN_WIDTH = 800
SCREEN_HEIGHT = 600

screen = pygame.display.set_mode((SCREEN_WIDTH, SCREEN_HEIGHT))
pygame.display.set_caption("Escape the Platforms")

clock = pygame.time.Clock()

player_rect = pygame.Rect(100, 500, 40, 60)
player_speed = 5
player_y_velocity = 0

gravity = 0.5
jump_strength = -12
on_ground = False

platforms = [
    pygame.Rect(0, 580, 800, 20),
    pygame.Rect(150, 480, 200, 20),
    pygame.Rect(450, 380, 200, 20),
    pygame.Rect(250, 280, 180, 20)
]

running = True

while running:
    clock.tick(60)

    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            running = False

    keys = pygame.key.get_pressed()

    # Horizontal movement
    if keys[pygame.K_LEFT]:
        player_rect.x -= player_speed

    if keys[pygame.K_RIGHT]:
        player_rect.x += player_speed

    # Screen boundary checks
    if player_rect.left < 0:
        player_rect.left = 0

    if player_rect.right > SCREEN_WIDTH:
        player_rect.right = SCREEN_WIDTH

    # Jumping
    if keys[pygame.K_SPACE] and on_ground:
        player_y_velocity = jump_strength
        on_ground = False

    # Apply gravity
    player_y_velocity += gravity
    player_rect.y += player_y_velocity

    # Assume the player is not on the ground until a platform proves otherwise
    on_ground = False

    # Platform collision detection
    for platform in platforms:
        if player_rect.colliderect(platform) and player_y_velocity > 0:
            player_rect.bottom = platform.top
            player_y_velocity = 0
            on_ground = True

    # Draw everything
    screen.fill((255, 255, 255))

    for platform in platforms:
        pygame.draw.rect(screen, (0, 0, 0), platform)

    pygame.draw.rect(screen, (0, 0, 255), player_rect)

    pygame.display.update()

pygame.quit()

This is a major step forward.

The player now interacts with platforms.

The player can jump, fall and land on different surfaces.

The level is still basic, but it is becoming a real platform game.

Why on_ground = False Is Reset Each Frame

This line is important:

on_ground = False

It appears before checking platform collisions.

At first, this may look strange.

Why set on_ground to False when the player might be on a platform?

The reason is that each frame, the program should check the current situation again.

The player is assumed to be in the air unless a collision with a platform proves they are standing on something.

If the player is touching a platform from above, the collision code sets:

on_ground = True

This keeps the jumping logic accurate.

Without this, the game might incorrectly think the player is still on the ground after walking off the edge of a platform.

That is an excellent bug to discuss in the project write-up.

The Walk-Off-the-Platform Problem

One of the most important tests is what happens when the player walks off a platform.

The expected result is simple:

The player should fall.

However, if the on_ground variable is not updated correctly, the player may be able to jump in mid-air after walking off the edge.

That would be a bug.

The solution is to reset on_ground each frame and only set it to True when a platform collision confirms that the player is standing on something.

This is a good example of state management.

The program must keep track of whether the player is grounded, but that state must be checked and updated continuously.

Common Collision Detection Bugs

This stage is likely to produce bugs. That is not a failure. It is exactly why this makes a good A Level project.

Bug 1: The Player Falls Through Platforms

This can happen if the player is moving too fast or if the collision check is in the wrong place.

Possible fixes include:

• checking collisions after vertical movement

• reducing gravity

• limiting the maximum falling speed

• checking whether the player was above the platform in the previous frame

Bug 2: The Player Gets Stuck Inside a Platform

This often happens when the player overlaps a platform but is not moved back to a safe position.

A simple fix is:

player_rect.bottom = platform.top

This places the player exactly on top of the platform.

Bug 3: The Player Can Jump After Walking Off a Platform

This usually happens because on_ground remains True after the player leaves the platform.

Resetting on_ground each frame helps solve this.

Bug 4: The Player Lands on the Side of a Platform

If the collision detection is too simple, the game may treat a side collision as a landing.

This is one reason why more advanced collision detection often separates horizontal and vertical movement.

For now, we are focusing mainly on landing from above. Later, students may improve the algorithm to handle side collisions more accurately.

Separating Horizontal and Vertical Collision

A more advanced approach is to deal with horizontal and vertical movement separately.

The program can:

1. Move the player horizontally.

2. Check for side collisions.

3. Move the player vertically.

4. Check for floor or ceiling collisions.

This is more complex, but it gives better control.

For example, if the player moves horizontally into a wall, the program can stop sideways movement without affecting vertical movement.

If the player falls onto a platform, the program can stop vertical movement without affecting horizontal movement.

This is something students could add as an extension once the basic version works.

It would also make a strong discussion point in the evaluation.

Using Platform Data for Future Levels

At the moment, our platforms are stored like this:

platforms = [
    pygame.Rect(0, 580, 800, 20),
    pygame.Rect(150, 480, 200, 20),
    pygame.Rect(450, 380, 200, 20),
    pygame.Rect(250, 280, 180, 20)
]

This is already a simple form of level design.

If we change the numbers, we change the level.

For example, moving a platform higher makes the jump harder.
Making a platform narrower makes landing more difficult.
Placing platforms further apart changes the route.
Adding a platform creates a new possible path.

This is where students can begin to see the connection between code and game design.

The level is not just decoration. It is data.

In the next part of the series, we can develop this further by creating proper levels, perhaps storing them as lists, dictionaries or external files.

Designing a First Test Level

A good first test level should not be too difficult.

The aim is to test the mechanics, not frustrate the player.

A sensible first level might include:

• a wide ground platform

• one low platform that is easy to jump onto

• a second platform slightly higher

• a third platform further away

• a finish point that will be added later

For now, the goal is simply to check that the player can land on each platform.

Students should avoid making the platforms too small too early.

Difficult levels should come after reliable mechanics.

Testing Platforms and Collision Detection

Testing is essential at this stage.

Students should create a test table that checks normal movement and awkward cases.

Test Number	Test	Expected Result	Actual Result	Pass/Fail
1	Run the program	Player appears and platforms are visible	Player and platforms appear	Pass
2	Player falls onto ground platform	Player lands and stops falling	Player lands correctly	Pass
3	Jump onto first raised platform	Player lands on top of platform	Player lands correctly	Pass
4	Walk off a raised platform	Player falls downwards	Player falls correctly	Pass
5	Press jump while standing on platform	Player jumps upwards	Player jumps correctly	Pass
6	Press jump after walking off platform	Player should not jump again in mid-air	Player cannot jump in mid-air	Pass
7	Land on second platform	Player lands and can jump again	Player lands correctly	Pass
8	Hit side of platform	Player should not behave unpredictably	Needs improvement	Fail/Partial
9	Fall from top platform to ground	Player lands on lower surface	Player lands correctly	Pass
10	Move to screen edge	Player remains inside screen	Player remains inside screen	Pass

Notice that one test may not fully pass.

That is acceptable if it is recorded honestly.

A project that identifies limitations and suggests improvements is often stronger than one that pretends everything is perfect.

Linking Back to Success Criteria

This stage supports several success criteria from the planning article:

• The game contains several platforms.

• The player can stand on the top of each platform.

• The player falls when not standing on a platform.

• The player can jump from a platform.

• The player cannot repeatedly jump while in the air.

• The player can move left and right while jumping.

• The player remains within the screen boundaries.

Students should keep referring back to the original criteria.

This makes the project feel coherent rather than random.

A good development log entry might say:

This stage met the success criteria relating to platforms, jumping and landing. The player can now land on several rectangular platforms. Testing showed that walking off a platform causes the player to fall, which fixed an earlier problem where the player could still jump after leaving the platform.

That is strong project evidence.

Evidence Students Should Collect

For this stage, useful evidence might include:

• screenshot of the platform layout

• screenshot of the player standing on a platform

• screenshot of the player falling between platforms

• code showing the platform list

• code showing collision detection

• test table for landing and falling

• notes about bugs and fixes

• short video showing the player jumping between platforms

The most important thing is to collect evidence while the work is happening.

Trying to recreate evidence at the end of the project is much harder.

Personal Reflection: This Is Where Students Start to Understand Games Differently

This is one of my favourite stages when teaching programming projects.

At the beginning, students often think of games mainly in terms of graphics.

They talk about characters, backgrounds and visual style.

But when they add platforms and collision detection, they begin to see that a game is really a system of rules.

A platform is not just a rectangle.

It is something the player can stand on, fall from, jump from and interact with.

The program has to decide what touching means.

That is a powerful lesson.

Students begin to understand that programming is not simply making something appear on screen. It is defining behaviour.

That is why a simple retro platform game can be such a good project.

It looks small, but it contains real computational thinking.

Practical Task for Students

Before moving on to level design, students should complete this task.

Part 4 Student Task

Add platforms and collision detection to your platform game.

Your program should include:

1. At least four platforms, including the ground.

2. Platforms stored in a list.

3. A loop to draw all platforms.

4. A player rectangle used for collision detection.

5. Gravity applied each frame.

6. Collision detection between the player and platforms.

7. A landing response that places the player on top of the platform.

8. An on_ground variable that updates correctly.

9. A test table for platform collisions.

10. Screenshots or video evidence of the player landing on platforms.

Extension Task

Improve the platform system by adding one of the following:

• side collision detection

• ceiling collision detection

• moving platforms

• one-way platforms

• different platform types

• platforms stored in a separate level data structure

• a simple finish point

• a debug mode showing collision rectangles

Students should only attempt extensions once the basic collision detection is reliable.

Development Log Example

A good development log entry might look like this:

Development Stage

Adding platforms and collision detection.

Aim

To allow the player to land on raised platforms instead of only landing on the bottom of the screen.

What Was Added

• platform list

• platform drawing loop

• player rectangle for collision detection

• collision detection using rectangle overlap

• landing response when falling onto a platform

• updated on_ground logic

Problems Found

• The player could initially jump after walking off a platform.

• The player sometimes overlapped slightly with a platform before being corrected.

• Side collisions were not handled accurately in the first version.

Changes Made

• Reset on_ground to False each frame.

• Set on_ground to True only when landing on a platform.

• Set the bottom of the player rectangle to the top of the platform after collision.

• Recorded side collision as an area for later improvement.

Evidence Collected

• screenshots of the player on platforms

• code showing the platform list

• code showing collision detection

• test table

• notes explaining the walk-off-platform bug

This sort of development record is exactly what students need for a strong A Level project.

Preparing for Levels

Once platforms work, we are ready for the next major step: level design.

A level is more than a random collection of platforms.

A good level has:

• a start point

• a route

• increasing challenge

• safe areas

• risk areas

• a finish point

• opportunities for scoring

• suitable difficulty for the target user

At the moment, our platforms are hard-coded into one list.

That is fine for the prototype.

But as the game grows, we can improve this by storing levels as separate data structures.

For example, we might eventually have:

level_1_platforms = [...]
level_2_platforms = [...]
level_3_platforms = [...]

Or we might store level data in dictionaries:

level_1 = {
    "platforms": [...],
    "player_start": (100, 500),
    "finish": (700, 520)
}

This opens the door to multiple levels.

It also creates excellent A Level project material because the student can explain how the game data is organised.

Final Thoughts: Collision Detection Turns Movement Into a Game

Adding platforms and collision detection is a major step in the project.

The player is no longer just moving around a blank screen.

The player is now interacting with a world.

They can jump onto platforms, fall from them, land on them and begin to move through a level.

This stage also creates some of the best learning moments in the whole project. The bugs are real. The problems are interesting. The solutions require thought.

The player may fall through platforms.
They may get stuck.
They may jump when they should not.
They may collide from the side in unexpected ways.

All of that is valuable.

A good A Level project is not one where everything works perfectly first time. It is one where the student can show how they found problems, tested them, improved the program and explained the decisions they made.

With platforms now working, the project is ready to move from mechanics to design.

In the next article, we will look at how to turn these platforms into proper levels, with routes, difficulty, start points, finish points, collectables and hazards.

 

Making Something Useful from Chemistry: Building a Lead–Acid Accumulator

Chemistry lessons often involve colour changes, precipitates, gases and equations. These can be interesting, but students sometimes leave the laboratory wondering what any of it is actually for.

Making a simple lead–acid accumulator changes that.

Using two carefully prepared lead sheets, dilute sulfuric acid, beakers, connecting wires and a low-voltage power supply, it is possible to construct a device that stores electrical energy chemically. After charging it for only a few minutes, the accumulator can be disconnected from the supply and used to light a small bulb.

For a student, that moment is important.

The bulb may not be especially bright and it may not stay illuminated for very long, but the electricity is no longer coming directly from the power supply. Energy has been stored inside the chemicals and then released again.

That is chemistry doing something useful.

A Battery Built in the Laboratory

The basic apparatus looks surprisingly simple:

• two lead sheets;

• dilute sulfuric acid;

• a beaker;

• connecting wires;

• a low-voltage direct-current supply;

• an ammeter and voltmeter;

• a small bulb or suitable low-voltage load.

The lead sheets first need careful preparation. Grease, dirt and surface contamination can prevent good contact between the metal and the electrolyte. In our experiment, the sheets were degreased and soaked in sodium hydroxide solution for approximately 10 minutes before being rinsed and placed in the sulfuric acid.

This preparation is not merely tidying the apparatus. It is part of the science.

Electrochemical reactions happen at the surfaces of the electrodes. A contaminated surface can reduce the effective area available for reaction, increase the internal resistance and make the results much less reliable.

The Royal Society of Chemistry describes a comparable classroom experiment using lead strips and dilute sulfuric acid to demonstrate the operation of a rechargeable lead–acid accumulator.

An Important Correction: An Accumulator Is a Rechargeable Battery

It is easy to describe the investigation as exploring why accumulators are used in cars rather than rechargeable batteries. However, a lead–acid accumulator is a rechargeable battery.

The useful comparison is between a lead–acid accumulator and other rechargeable technologies, such as:

• lithium-ion batteries;

• nickel-metal hydride batteries;

• rechargeable alkaline systems;

• newer solid-state or sodium-ion technologies.

The word accumulator emphasises that the device accumulates or stores electrical energy. In modern everyday language, we are more likely to call it a rechargeable battery.

A single lead–acid cell produces a voltage of roughly two volts. A conventional 12-volt car battery contains six such cells connected in series.

Our beaker cell was therefore not intended to reproduce the full performance of a car battery. It was a model that allowed us to investigate the same underlying chemistry.

What Happens During Charging?

Initially, both electrodes are lead. When the cell is connected to a direct-current supply, electrical energy forces chemical changes to take place at their surfaces.

The electrode connected to the positive terminal gradually develops a coating containing lead dioxide, PbO₂. The negative electrode remains largely as lead, although its surface becomes more active and porous.

The charging process is an example of electrolysis. A non-spontaneous chemical change is being driven by an external source of electricity.

This is one of the most useful links students can make between different parts of chemistry. Electrolysis is not simply about producing copper at an electrode or splitting a molten ionic compound. It can also be used to place a chemical system into a higher-energy state.

The electrical supply does not disappear into the cell. Its energy is stored through chemical changes in the electrodes and electrolyte.

What Happens During Discharge?

After charging, the power supply is removed and the cell is connected to a bulb.

The chemical reactions now proceed in the opposite direction. Electrons flow through the external circuit from the negative electrode, through the bulb and towards the positive electrode.

At the negative electrode, lead reacts with sulfate ions:

Pb + SO₄²⁻ → PbSO₄ + 2e⁻

At the positive electrode, lead dioxide reacts with hydrogen ions, sulfate ions and electrons:

PbO₂ + 4H⁺ + SO₄²⁻ + 2e⁻ → PbSO₄ + 2H₂O

The overall discharge reaction is:

Pb + PbO₂ + 2H₂SO₄ → 2PbSO₄ + 2H₂O

Both electrodes gradually become coated with lead sulfate. At the same time, sulfuric acid is consumed and water is formed.

The stored chemical energy is converted back into electrical energy, which is then transferred by the bulb into light and thermal energy.

The Moment the Bulb Lights

There is something particularly satisfying about disconnecting the charging supply, attaching the bulb and seeing it light.

Before that moment, the experiment can appear to be little more than two grey pieces of metal sitting in a colourless liquid. There is no dramatic flame, vivid colour or obvious movement.

Then the bulb glows.

It provides visible evidence that something has changed inside the cell.

This is why practical chemistry matters. A diagram of a lead–acid cell can show the electrodes and equations, but it cannot reproduce the experience of making one work.

The glow of the bulb creates questions:

• Where did the energy come from?

• Why does the bulb gradually become dimmer?

• Why does the terminal voltage fall?

• Can the cell be recharged?

• How much of the original energy is recovered?

• What limits its performance?

These questions turn a demonstration into a genuine scientific investigation.

Measuring the Charging Energy

To calculate the efficiency of the accumulator, we first need to estimate how much electrical energy is supplied during charging.

Electrical energy is calculated using:

Energy = potential difference × current × time

or:

E = VIt

where:

• E is energy in joules;

• V is potential difference in volts;

• I is current in amperes;

• t is time in seconds.

Suppose the accumulator is charged at:

• 3.0 V;

• 0.40 A;

• for 300 seconds.

The charging energy would be:

E = 3.0 × 0.40 × 300

E = 360 J

This assumes that the voltage and current remain approximately constant. For a more accurate investigation, readings should be taken at regular intervals and the energy calculated from the area beneath a power–time graph.

Because:

Power = voltage × current

we can plot power against time. The area beneath that graph represents the electrical energy supplied.

Measuring the Energy Recovered

The charged accumulator is then connected to the bulb or another suitable resistor.

The output energy can again be estimated using:

E = VIt

Suppose the bulb operates with an average potential difference of 1.7 V and an average current of 0.15 A for 240 seconds.

The recovered electrical energy would be:

E = 1.7 × 0.15 × 240

E = 61.2 J

The energy efficiency would then be:

Efficiency = useful energy output ÷ total energy input × 100

Efficiency = 61.2 ÷ 360 × 100

Efficiency = 17%

A simple classroom cell may have quite a low efficiency. That does not mean the experiment has failed. It gives us something more interesting to investigate.

Where Does the Missing Energy Go?

Energy is conserved, but not all of the charging energy can be recovered as useful electrical energy.

Some is transferred through:

• heating of the electrolyte;

• heating of the wires and electrodes;

• electrical resistance inside the cell;

• unwanted gas production;

• incomplete or competing chemical reactions;

• energy remaining chemically stored when the test is stopped;

• losses caused by contamination or poor electrode contact.

The bulb itself also converts only part of its electrical input into visible light. Much of the energy becomes thermal energy.

This creates an important distinction.

If we are calculating the electrical efficiency of the accumulator, the useful output is the electrical energy delivered to the bulb.

If we are calculating the efficiency of the complete system as a source of visible light, we would also need to consider the efficiency of the bulb.

That is a much more difficult measurement.

Making the Investigation More Scientific

A single successful demonstration proves that the accumulator can store energy. A proper investigation asks what affects its performance.

Students could investigate:

Charging time

Does doubling the charging time double the energy recovered?

At first, a longer charging period may increase the discharge time. Eventually, however, further charging may produce diminishing returns or encourage unwanted reactions.

Electrode surface area

Larger electrodes provide more surface area for electrochemical reactions. This may reduce internal resistance and allow a larger current to flow.

Distance between the electrodes

Moving the electrodes further apart increases the distance ions must travel through the electrolyte. This can increase resistance and reduce the current.

The electrodes must not touch, as this would short-circuit the cell.

Condition of the lead surfaces

Clean, roughened or porous surfaces may behave differently from smooth or contaminated surfaces.

This makes the lengthy preparation of the lead sheets scientifically significant rather than merely procedural.

Discharge current

A small load may allow the accumulator to operate for longer, while a low-resistance load may draw a larger current but discharge the cell rapidly.

Number of cells

Cells can be connected in series to increase the voltage. They can also be connected in parallel to increase current capacity, although this requires cells with closely matched characteristics.

Voltage Is Not the Same as Stored Energy

Students sometimes measure the terminal voltage and assume that the cell with the highest voltage stores the most energy.

That is not necessarily true.

A cell can produce a measurable voltage but be unable to maintain that voltage when a significant current is drawn. Its internal resistance may be high, or only a small quantity of reactant may be available.

A useful battery must provide both:

• an appropriate voltage;

• sufficient current for a useful length of time.

This is why measuring only the open-circuit voltage gives an incomplete picture.

The accumulator should also be tested under load. Measuring voltage and current while the bulb is operating reveals much more about its actual performance.

Why Lead–Acid Batteries Are Used in Cars

A petrol or diesel engine needs a substantial burst of electrical power to operate its starter motor. Turning the engine requires a very large current for a relatively short time.

Lead–acid batteries are well suited to this job because they can be designed to provide high power, are relatively inexpensive and have a long-established reputation for reliability. Their disadvantages include low energy per unit mass and a shorter cycle life than some newer chemistries.

This is the central point.

A traditional car battery does not need to provide moderate power for hundreds of kilometres. Its main job is to supply a brief but powerful starting current and then support the vehicle’s electrical systems. Once the engine is running, the alternator recharges it.

Lead–acid batteries are also used for stop–start systems and for ancillary electrical loads in some electric vehicles. The main traction batteries in modern electric vehicles are usually lithium-ion because lithium-ion cells store considerably more energy for their mass and volume.

Why Not Use Lithium-Ion for Every Car Battery?

Lithium-ion batteries are lighter and have much greater energy density. That makes them ideal when weight and stored energy are critical, especially in electric vehicles, phones and laptops.

However, a vehicle’s low-voltage battery has different requirements.

It must be:

• dependable;

• capable of delivering high current;

• tolerant of repeated charging;

• economical to replace;

• compatible with established vehicle charging systems;

• supported by a reliable recycling network.

Lead–acid technology is mature, widely available and comparatively inexpensive. Replacing it is not simply a question of finding a battery that stores more energy. The replacement must satisfy the whole engineering specification.

This is an excellent example of why engineers rarely ask, “Which material is best?”

They ask, “Which material is best for this particular job?”

The Environmental Question

Lead is toxic, and sulfuric acid is corrosive. A lead–acid battery should never be treated as ordinary rubbish.

The technology remains viable partly because collection and recycling systems are already well established. The US Environmental Protection Agency reports a 99% recycling rate for lead–acid batteries in its cited national data and describes a collection network involving retailers, manufacturers and specialist recyclers.

High recycling rates do not make lead harmless. They demonstrate the importance of designing a complete system around a hazardous but useful material.

The environmental judgement therefore cannot be based only on what happens while the battery is inside the car. It must include:

• extraction of raw materials;

• manufacturing;

• working life;

• maintenance;

• collection;

• recycling;

• safe handling of lead and acid;

• prevention of contamination.

This wider life-cycle thinking is increasingly important across science and engineering.

Safety Must Come First

This is not a casual home experiment.

Sulfuric acid is corrosive, sodium hydroxide is corrosive, lead is toxic, and charging can produce gases if the conditions are not properly controlled. The activity should only be carried out in a suitably equipped laboratory under competent supervision, using an approved risk assessment and appropriate local guidance.

Essential precautions include:

• suitable eye protection and protective clothing;

• careful control of acid and alkali concentrations;

• good ventilation;

• avoiding flames and ignition sources;

• using a current-limited low-voltage supply;

• preventing the electrodes from touching;

• washing hands thoroughly after handling lead;

• collecting all lead-containing materials and solutions as hazardous waste;

• never pouring lead-contaminated liquids down a sink.

The purpose of the experiment is to teach electrochemistry, not to reproduce a commercial battery without industrial safeguards.

From a Beaker to a Car

The laboratory accumulator is small, inefficient and temporary. A car battery is sealed, carefully engineered and constructed with many plates to provide a very large effective surface area.

Yet both depend on the same principles:

• oxidation and reduction;

• movement of electrons through an external circuit;

• movement of ions through an electrolyte;

• reversible chemical reactions;

• conversion between electrical and chemical energy.

That connection is what makes the investigation so valuable.

Students are not simply memorising half-equations. They are seeing how those equations describe a working energy-storage device.

Chemistry That Earns Its Place

I find experiments like this particularly valuable because they answer a question students often do not ask aloud:

Why are we learning this?

We learn about ions because their movement allows charge to be transported through an electrolyte.

We learn about oxidation states because electrons are transferred during charging and discharging.

We learn about electrolysis because electrical energy can drive chemical change.

We learn about energy calculations because a working device must be measured, compared and improved.

We learn about efficiency because no real system returns all the energy supplied to it in a useful form.

Most importantly, we learn that chemistry is not confined to bottles on a laboratory shelf. It is inside vehicles, phones, emergency power systems, renewable-energy installations and almost every modern electrical device.

Conclusion: When the Chemistry Becomes Real

Two pieces of prepared lead, a beaker of sulfuric acid and some wires do not initially look like an energy-storage system.

After a few minutes of charging, however, they can light a bulb.

That small glow represents a remarkable sequence of energy transfers. Electrical energy has driven chemical reactions, the products have stored energy, and the reverse reactions have released electrical energy into a circuit.

The accumulator may not be especially efficient. Its voltage may fall rapidly and its light may be brief. Those limitations are not reasons to dismiss it. They are opportunities to measure, explain and improve it.

The experiment brings together redox chemistry, electrolysis, electrical circuits, energy, power, efficiency, materials science and environmental responsibility.

Above all, it shows students that chemistry can make something genuinely useful.

Sometimes the best way to understand a battery is not merely to draw one.

It is to build one, charge it and watch the bulb come on.