Grade 5 Math Book · Big Numbers & Place Value
The King's Chessboard
by David Birch
A wise man asks the proud king for a reward: one grain of rice on the first square of a chessboard, two on the next, then four, doubling for every square. The king agrees, and soon learns how fast doubling grows.
Why it's useful
A classic tale that shows exponential growth in a way kids never forget.
- Doubling patterns. 1, 2, 4, 8, 16… kids see how quickly the numbers explode.
- Powers of 2. A natural introduction to exponents.
- Estimation. Kids guess how much rice the king owes, then check.
Try it in class or at home
- Predict first. Before reading, ask how many grains will be on the last square. Write down guesses.
- Double it. Fill in the first 20 squares as a class with calculators.
- Compare. Would you rather have $1,000 a day for a month or 1¢ doubled every day? Work it out.