Prime Numbers Challenge
in Numeracy
This practice helps children understand the concept of prime numbers through a self-made card game.
First explain the concept of prime numbers. In brief, prime number is a natural number which can be divided only with two numbers: 1 and itself (e.g. 2, 3, 5, 7, 11...)
Number 18 cards, pieces of paper, or bottle caps with the numbers 1 – 18. Mix them up and arrange them face
down in a grid – 6 cards per row, 3 cards per column.
Have one child turn over one card. Ask another child turn over
a second card - if they add them together, what is the sum? Is the sum a prime number?
• If yes, move the two cards to the side in a pair
• If not, turn them back over and continue to play the game
The game ends when you cannot find any more pairs that make a prime number.
Activity extension: Add subtraction! When the two cards are turned over, do they subtract to make a prime number?
Activity extension: Add multiplication! Multiply the two numbers to see whether they make a prime number. Why do most pairs or numbers not make a prime number when multiplied together?