Sophie Duncan suggests giving a 19th-century children's toy a spin
This device was a favourite children's toy from the 1860s. It was invented by William George Horner in 1834, and still captivates its users.
Its name was made up from two Greek words meaning turning living things. It is a zoetrope.
Making a simple zoetrope is an excellent way to explore the persistence of vision with your students. A zoetrope can be made any size. Find a circular cardboard lid from an ice-cream container or similar for the base. Paint it black. Measure the diameter of the lid, and calculate the circumference by multiplying the diameter by pi.
Cut a strip of black cardboard 10cm wide and just longer than the circumference. This strip of card needs to have a number of slots cut into it from the top. These should be about 0.5cm wide and 6cm long, and equidistant about 3cm apart. Attach this strip to the base, ensuring that it sits inside the lip of the lid and is secured. Make a hole in the base of the lid and push a thin stick, such as a flower cane, through the hole.
Attach it to the zoetrope using Blu-Tack. Thread the stick through a straw, so that you can hold the straw and turn the zoetrope. To make the animation cut a strip of white paper 4cm wide and slightly more than the circumference of the lid, making sure the extra bit of length is marked to avoid using this in your design. Divide the strip into a number of squares of equal size. The number of squares should be about the same as the number of slots. Draw your images inside these squares making sure that each image changes slightly from one square to the next and ensuring the last image leads naturally to the first. An easy example is to use a round sticker as a ball, and place it as if the ball were bouncing up and down. Secure the finished strip inside the zoetrope and spin it in a well-lit area. View the images through one of the slots.
Sophie Duncan is project manager for science at the BBC www.bbc.co.ukscience