Children's Museum of Houston

Did you know?

What you need

What to do

1. The first person is the caller; the other two are the “numbered heads”.
2. Each numbered head needs a set of 10 cards. Place the cards face down.
3. Each numbered head picks up a card without looking at what is on it and holds the card on his forehead so the other numbered head and the caller can see it.
4. The caller says the sum of both the cards. Then the numbered heads must figure out what they are holding on their own forehead. (In the beginning you may want to use actual objects to represent the sum.)
5. The first to correctly shout out what is on their head wins and becomes the next caller.

What to ask

• How did you get your answer?
• What are fast ways to get the answer?
• Are some strategies better than others are? Why? When?

What’s next?

• Make up a story problem that represents the numbers on the numbered heads. Remember in this game you know the total and one of the numbered heads and are asked to find the other.  Some examples of problems that model this are:
  • Freddie has 14 feathers. 4 are green and the rest are blue. How many are blue? OR,
  • Gabriela has 4 hair bows and she wants to have 12. How many hair bows does she need to buy? Write and illustrate your problem.
• Use numbers 11 to 20.
• Add a third numbered head.