How many guesses?

Steps

1. Ask: you lent a book to a friend and forgot who. You visit six houses. How many visits will you need?
2. Each child writes a guess on a sticky note and puts it on a line from 1 to 6.
3. Lay out 15 cards animal-side up. The numbers underneath are in no order.
4. Pick a target number. A child turns over cards one at a time until they find it, while the class counts.
5. Try again with different targets. Write the number of guesses each time.
6. Look at the results. Was it ever the first card? The last?

Talk about it

• Is it ever fast to search when nothing is in order?
• What is the most guesses you could need?
• How could we make searching faster?