Useful for a lesson on different ways we send messages by light, in how we see things or a more general light topic this work sheet provides cross curricular links to maths and history and possibly fundamental British values as well as talking about broadband which means you can spring off into many different routes. The main challenge is for the pupils to independently make a code to send a message in pairs or groups as fast as possible. Often results in some great photos for sticking in workbooks, twitter feeds etc. Make the pupils do the work and get maximum science exposure! Useful for KS 3 and Common entrance GCSE, middle school and older depending on how you work the connections to other topics and subjects.