Binary cards- the maths behind the magic

Promethean flipchart/worksheet/5cards per pupil A nice activity in which pupils investigate base 2. Start by displaying the cards and doing the trick (e.g.ACD = 13)with your back to the board (most of them will be amazed). Tell them that they too will be able to do this trick by the end of the lesson. Discuss denary and possible reasons for its use. Move onto binary giving examples of modern day uses ( computers, mobile phones etc). Pupils find binary codes for 1 - 31 on the worksheet. The columns on the worksheet are A - E from right to left and a 1 indicates which cards should have that number (e.g. 5 base 10 =00101 - columns A and C have a 1 and so should have 5 written on them. Pupils create their own 5 cards and practise the trick.