This Science video introduces teachers to using and creating classification keys to sort organisms based on similarities and differences. It explains how branching keys use a series of yes/no questions to guide users towards identifying an organism, and demonstrates the process with a worked example of sorting vertebrates. Pupils are shown how to follow a key accurately and how to create their own by thinking of questions that divide groups into two smaller groups at each step.

This Science video introduces teachers to the key learning in this unit, where pupils explore how light behaves and how shadows form. Light is a store of energy that travels in waves and does not need particles to move, which is why it can travel through space.