Codes for letters using binary representation

Steps

1. Ask: how does a computer know which letter to show? Count the letters of the alphabet together.
2. Explain that A is 1, B is 2, C is 3, and so on.
3. Put the five cards in a row, biggest on the left (16, 8, 4, 2, 1).
4. Say a pattern such as No, Yes, No, No, No. The cards with Yes are on. Add the dots: that is 8, which is the letter H.
5. Say No, Yes, No, No, Yes. That is 9, the letter I. Together they spell HI.
6. Let the children choose a short word, work out its codes, and send it to a partner who decodes it.

Talk about it

• Why do we need a fifth card?
• Could we use other words than yes and no, like up and down?
• What other things on a keyboard need a code?