Old Maths Papers

 I had not realised that back in 1983, for example, different Maths Syllabi shared the same papers—this is for the London Board—i.e., Pure Maths 3 was the same as Further Maths Syllabus B, and most A-level Maths students these days would struggle to pass this.

Gates

 Computing in the Holidays: Making a computer from scratch - learning how AND, NOT, OR and XOR gates work. Creating the circuits to make the students own truth tables is a far more effective way of learning and understanding them.

Making Salts

 GCSE Chemistry in the Holidays. Core experiments are in the exams so practicing them, understanding what is going on and trying out different ones other than making copper sulfate is essential to improving grades.

Smartcart with Fan

 Physics in the Holidays. There is time to investigate how the angle of the fan on this @pascoscientific smartcart affects its forward direction. By placing a mast and sail on a smartcart, we can see how the wind's direction and the sail's angle allow the cart to move towards the wind.

Biased Dice

 Maths in the Holidays—Many questions in exams and elsewhere feature biased dice, but the students have no idea what these are, so getting a set of biased dice and then letting the students play with them to work out each dice's probability of throwing a particular number is fun.

Applications of electromagnetic induction

 21st Cent Physics in the Holidays. Going through some revision of transformers and the rules of induction then applying their use in the national grid.

Extracting DNA

 A-level Biology in the Holidays. Extracting DNA from different fruits, such as in the picture of strawberries. Once extracted, the DNA can be used for molecular analyses, including PCR, electrophoresis, sequencing, fingerprinting and cloning.