Squeezing pictures into less space

Steps

1. Show an 8 by 8 picture made of black and white squares. Ask how you could describe it without naming every square.
2. Teach the trick: instead of naming each square, count how many of the same colour come in a row.
3. Do the first row together. Start with white. For example, 3 white then 2 black then 3 white becomes 3, 2, 3.
4. Let children write the code for the other rows.
5. Swap codes with a partner. Each partner colours the picture back from the code.
6. Compare: did the code use fewer numbers than the 64 squares?

Talk about it

• Which pictures squeeze well, and which do not?
• Why do computers want to use less space?
• Where have you seen pictures that were sent or saved?