04 November 2025

Conservation of Momentum in Two Dimensions

The law of conservation of momentum states that in a closed system, the total momentum before and after a collision remains the same, provided no external forces act. Most students first encounter this concept in one dimension, but momentum becomes much more interesting when collisions occur at angles. Using an air hockey table or an air puck system, students can observe momentum conservation in two dimensions and see the theory unfold frame by frame.

The Experiment

An air hockey table or an air track with gliders provides a near-frictionless surface. Two pucks are set on a collision path, either head-on or at an angle. A top-down video camera records the collision.

Using software such as PASCO Capstone, Tracker, or Logger Pro, students can:

Track each puck’s motion before and after impact.
Draw velocity vectors showing direction and magnitude.
Split momentum into x- and y-components and calculate totals before and after the collision.

Total momentum before = Total momentum after

m_1u_{1x} + m_2u_{2x} = m_1v_{1x} + m_2v_{2x}

m_1u_{1y} + m_2u_{2y} = m_1v_{1y} + m_2v_{2y}

The results show that even when the pucks scatter in different directions, the total momentum in both axes remains constant.

The Science

Collisions can be elastic (kinetic energy conserved) or inelastic (some energy lost as heat or deformation). However, momentum is always conserved.
The vector approach shows that momentum is not just about speed but direction — making it essential for understanding real-world physics such as vehicle collisions, snooker impacts, or atomic interactions.

Skills Highlight

Recording and analysing motion using video tracking
Decomposing vectors into x- and y-components
Verifying conservation laws experimentally
Linking abstract vector mathematics to physical evidence

Why It Works in Teaching

The combination of air hockey, sensors, and video analysis makes an abstract law tangible. Students can see how momentum balances in both directions, not through equations alone but through real motion, geometry, and evidence.

03 November 2025

Investigating Photosynthetic Pigments with a Pasco Spectrometer

Photosynthesis depends on a range of pigments that capture light energy from different parts of the spectrum. While chlorophyll dominates, other pigments, such as carotenoids and xanthophylls, also contribute, extending the range of light that plants can use. Using a PASCO spectrometer and coloured filters, students can investigate how different wavelengths affect light absorption — and discover why plants aren’t simply “green.”

The Experiment

Students set up a PASCO light sensor with a white light source and a series of coloured filters (red, blue, and green).
They:

Measure the light intensity passing through a pigment extract or leaf sample at each wavelength.
Record how much light is absorbed (low transmission) or reflected (high transmission).
Plot a spectral absorption graph, showing how pigment extracts respond to different colours of light.

Alternatively, a PASCO spectrometer can be used to collect continuous absorption data across the visible spectrum.

The Science

Each pigment absorbs specific wavelengths of light due to the arrangement of its electrons.

Chlorophyll a absorbs mainly red and blue light, reflecting green.
Chlorophyll b, carotenoids, and xanthophylls absorb in slightly different regions, broadening the plant’s overall light-harvesting ability.

By comparing absorption and photosynthesis rates, students can link pigment properties to plant adaptation and efficiency in different environments.

Plants contain a variety of photosynthetic pigments, primarily

chlorophylls and carotenoids (which include carotenes and xanthophylls), that allow them to absorb a broader range of light wavelengths for photosynthesis. These different pigments can be separated and identified using chromatography.

Plants with Different Photosynthetic Pigments

While most green plants contain the same primary pigments, the relative abundance and specific types can vary, particularly across different plant and algal groups:

Different plants to test could include:

Green leaves (e.g., spinach, grass) for typical chlorophylls and carotenoids.
Red or purple leaves (e.g., red cabbage, some Ficus benjamina cultivars) to observe anthocyanins (though these are not photosynthetic pigments, they co-exist).
Brown algae (seaweed) contain chlorophyll c and fucoxanthin.
Carrots or corn for high amounts of carotenes and xanthophylls, respectively.

Testing Photosynthetic Pigments

The standard method for separating and identifying these pigments is chromatography (paper or thin-layer chromatography, TLC), often followed by spectrophotometry.

Materials

Leaf samples (e.g., spinach, a red leaf variety)
Pestle and mortar
Acetone (organic solvent)
Chromatography paper or TLC plate
Chromatography solvent (e.g., a mixture of petroleum ether, acetone, and trichloromethane)
Capillary tube
Pencil and ruler
Beaker or test tube with a cover

Procedure (Thin-Layer Chromatography)

Extract the pigments: Grind a piece of leaf tissue in a mortar and pestle with a small amount of acetone to break open the cells and dissolve the pigments.

Spot the plate: Draw a pencil line near the bottom of a TLC plate. Use a capillary tube to repeatedly spot the pigment extract onto the line, allowing each spot to dry before applying the next, to create a concentrated spot.
Develop the chromatogram: Place the plate in a beaker containing a shallow layer of chromatography solvent, ensuring the solvent level is below the pencil line. Seal the container to saturate the atmosphere with solvent vapour.
Separate the pigments: Allow the solvent (mobile phase) to move up the plate by capillary action. Different pigments travel at different speeds because they vary in size and solubility in the mobile phase compared to their affinity for the stationary phase (the plate material).
Analyse the results: Once the solvent has nearly reached the top, remove the plate and immediately mark the solvent front with a pencil. You will see colored spots (bands) at different heights.
Identify pigments:
- Colour: Carotenes (orange) travel furthest, followed by xanthophylls (yellow), chlorophyll a (blue-green), and chlorophyll b (yellow-green).
- Rf value: Calculate the retention factor (Rf) for each pigment using the formula:
  $cap R sub f equals the fraction with numerator distance travelled by pigment and denominator distance travelled by solvent end-fraction$
- Compare the calculated Rf values to known standards for identification.
Further testing: The individual pigment bands can be scraped off the TLC plate, dissolved in a suitable solvent (e.g., alcohol), and analysed using a spectrophotometer to determine their specific light absorption spectrum. This confirms which wavelengths each pigment absorbs most effectively.

Skills Highlight

Using spectrometers to measure light absorption.
Plotting and interpreting graphs of intensity vs wavelength.
Relating pigment chemistry to photosynthetic efficiency.
Understanding experimental design and controlled variables.

Why It Works in Teaching

This investigation turns colour into data. Students can see the relationship between wavelength, absorption, and plant adaptation — a clear, visual link between physics and biology that strengthens understanding of photosynthesis.

02 November 2025

The Role of the Family in Modern Society

The family has long been seen as the cornerstone of social life, shaping identity, behaviour, and values. Yet, in modern society, the meaning and structure of “family” have undergone dramatic changes. A-Level Sociology students study these shifts to understand how social institutions adapt to cultural, economic, and technological change.

The Functionalist View

Functionalist sociologists such as Parsons and Murdock see the family as performing vital functions for both individuals and society. These include:

Socialisation: Teaching children norms, values, and culture.
Stabilisation: Providing emotional and economic support for members.
Reproduction: Ensuring the continuation of society.

Even as society evolves, Functionalists argue that the family remains central to maintaining social stability.

The Marxist and Feminist Perspectives

Marxists see the family as part of the capitalist system — a means of reproducing inequality. The family provides labour power, transmits property, and socialises children into accepting hierarchy and obedience.

Feminists, meanwhile, view the family as a site where gender inequality is reinforced. Traditional domestic roles and unpaid labour continue to disadvantage women, even as family forms diversify.

Both perspectives challenge the idea of the family as purely beneficial, arguing that it also reflects wider power structures.

The Postmodern and Contemporary View

In modern society, families take many forms: single-parent, reconstituted, same-sex, and cohabiting households. Sociologists such as Giddens and Beck describe this as part of a “risk society,” where individuals have more choice but also more uncertainty.

Modern families are less about fixed roles and more about negotiated relationships, built on shared values rather than traditional expectations. The rise of technology, dual incomes, and shifting gender norms has changed how families function — but not their emotional significance.

Skills Highlight

Comparing sociological perspectives on the family
Evaluating evidence for changing family roles
Understanding how social and economic change influences family life
Applying theory to contemporary examples

Why It Works in Teaching

Studying the family helps students connect sociological theory with their own experiences. It encourages critical thinking about the structures and values that shape society and helps individuals understand how personal relationships reflect broader social forces.

01 November 2025

Using Python Lists to Analyse Data Sets

Python is one of the most powerful tools for data analysis — and it all starts with the humble list. Lists allow students to store, sort, and process data efficiently, turning raw numbers into meaningful results. This simple programming concept introduces key computational thinking skills that underpin data science, statistics, and AI.

The Concept

A list in Python is a collection of data items stored under one variable name. Lists can hold numbers, text, or even other lists.

Example:


data = [12, 15, 18, 20, 22, 25]

From here, students can calculate averages, find maximum and minimum values, or even visualise data using libraries such as matplotlib.

The Experiment in Code


data = [12, 15, 18, 20, 22, 25]

mean = sum(data) / len(data)
max_value = max(data)
min_value = min(data)
sorted_data = sorted(data)

print("Mean:", mean)
print("Highest:", max_value)
print("Lowest:", min_value)
print("Sorted:", sorted_data)

The code above teaches iteration, built-in functions, and how to use Python as both a calculator and a simple data tool.

Students can then extend the activity to analyse real data — for example, daily temperatures, test results, or experiment readings — turning abstract numbers into trends and insights.

Skills Highlight

Creating and manipulating Python lists
Using built-in functions like sum(), max(), min(), and sorted()
Calculating statistical measures programmatically
Applying coding to practical data handling in science and maths

Why It Works in Teaching

Python bridges mathematics, computing, and science. Analysing data through code encourages logical thinking and problem solving. Students see instant feedback, gain confidence in coding, and learn a vital skill used in universities and industries worldwide.

31 October 2025

Making and Testing Esters – The Smell of Chemistry

Few experiments appeal to the senses quite like ester formation. When acids and alcohols react, they produce pleasant, fruity-smelling compounds called esters. From artificial flavours to perfumes and solvents, esters show how organic chemistry connects directly to everyday life.

The Experiment

Students mix a carboxylic acid with an alcohol in the presence of an acid catalyst — usually concentrated sulfuric acid.

A simple school-level method involves:

Placing 1 cm³ of alcohol and 1 cm³ of carboxylic acid into a test tube.
Adding a few drops of concentrated sulfuric acid.
Gently warming the mixture in a water bath for a few minutes.
Pouring it into a beaker of water to smell the resulting ester (wafting carefully, not directly).

Common examples include:

Alcohol	Carboxylic Acid	Ester Formed	Characteristic Smell
Ethanol	Ethanoic acid	Ethyl ethanoate	Pear or nail polish remover
Methanol	Butanoic acid	Methyl butanoate	Pineapple
Pentanol	Ethanoic acid	Pentyl ethanoate	Banana

The Science

The reaction is a condensation reaction, where two molecules combine and eliminate water:

\text{Alcohol} + \text{Carboxylic Acid} \rightarrow \text{Ester} + \text{Water}

Sulfuric acid acts as a catalyst and dehydrating agent, helping the equilibrium shift toward ester formation.

Students learn about reversible reactions, equilibrium position, and how structure determines smell.

Skills Highlight

Safely handling and heating volatile organic liquids
Observing and describing qualitative results (odour, appearance)
Understanding esterification as a reversible condensation reaction
Linking molecular structure to real-world products in industry and biology

Why It Works in Teaching

Making esters connects chemical theory with sensory experience. Students smell the result of their reaction and see chemistry as something tangible, memorable, and creative — a perfect example of applied organic chemistry.

30 October 2025

Demonstrating Boyle’s Law Using the PASCO Ideal Gas Equipment

Boyle’s Law shows one of the simplest and most elegant relationships in physics: when the temperature and mass of a gas remain constant, its pressure and volume are inversely proportional. Using PASCO’s ideal gas apparatus, students can see this relationship unfold through real-time measurements and perfectly smooth data.

The Experiment

The setup includes a PASCO Ideal Gas Apparatus with a pressure sensor and a movable piston connected to a syringe or sealed cylinder.

Students:

Trap a fixed amount of air in the cylinder.
Adjust the volume in measured steps using the piston.
Record the pressure at each point using the PASCO software.
Plot Pressure (P) against 1/Volume (1/V).

The resulting straight-line graph demonstrates that:

P \propto \frac{1}{V}

P \times V = \text{constant}

The Science

Boyle’s Law arises because gas molecules move randomly, colliding with container walls.
When volume decreases, molecules have less space, so collisions with the walls become more frequent — increasing pressure.

This fundamental law underpins much of physics, chemistry, and engineering — from scuba diving and weather balloons to piston engines and respiratory systems.

Skills Highlight

Using PASCO sensors to collect accurate, real-time pressure and volume data
Plotting and analysing inverse proportional relationships
Understanding molecular motion and the gas laws
Linking microscopic particle theory with macroscopic measurements

Why It Works in Teaching

PASCO equipment allows students to see a textbook law turn into live data. The smooth curve that straightens when plotted as $P$ against $1/V$ makes the proportionality unmistakable. It’s a visual, quantitative confirmation of kinetic theory in action.

29 October 2025

The Mathematics of Music – Ratios and Frequencies

Mathematics and music share a deep connection — both rely on patterns, structure, and proportion. When students explore musical notes and harmonies through ratios and frequencies, they see how simple numbers shape the sounds we hear every day.

The Concept

Musical notes are based on frequency, the number of vibrations per second (measured in hertz, Hz). When two notes are played together, the ratio of their frequencies determines how harmonious they sound.

For example:

Octave: 2:1 ratio (e.g., 440 Hz and 880 Hz)
Perfect fifth: 3:2 ratio (e.g., 440 Hz and 660 Hz)
Perfect fourth: 4:3 ratio
Major third: 5:4 ratio

These simple ratios create consonance — pleasant, stable sounds. More complex ratios produce dissonance, which gives tension and colour to music.

The Experiment

Students can use tuning forks, keyboard apps, or digital synthesiser tools to measure and compare frequencies. By analysing waveforms or using PASCO sound sensors, they can see how frequencies combine to form interference patterns and beats.

Plotting these waves shows visually why harmonious intervals have simple repeating patterns, while dissonant ones do not.

The Maths

If the frequency of a note is $f$ , then an octave above is $2f$ , and a fifth above is $\frac{3}{2}f$ .
Modern tuning (equal temperament) divides the octave into twelve semitones, where each note is $f \times 2^{1/12}$ times the frequency of the previous one — a perfect example of exponential growth in sound.

Skills Highlight

Exploring ratios and proportional reasoning in a musical context
Applying logarithmic and exponential relationships to real data
Visualising wave patterns and frequency combinations
Linking mathematical precision with creative expression

Why It Works in Teaching

This topic shows students that mathematics isn’t just abstract — it creates harmony, melody, and rhythm. Linking sound, frequency, and ratios provides a powerful and engaging way to explore number patterns and scientific thinking together.