Sieve of Eratosthenes

Grade 7

Created by:

Math & Movement

Activity Instructions

A prime number is a natural number that is greater than one and only has two factors, one and itself. Have your students use the Sieve of Eratosthenes to find all the prime numbers up to 100.
1. Stand on the number one. One is special – it is neither prime nor composite.
2. Step to the number two. This number is prime. Skip count by twos, covering all the multiples of two with black construction paper.
3. Move to the next number that is not covered with construction paper (in this case it will be three). Skip count by 3s and cover all the multiples of 3 with black construction paper.
4. Continue the same pattern until 100. The numbers not covered in black construction paper are the prime numbers.


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