Prime & Composite Numbers

A prime number is a whole number greater than 1, whose only two whole-number factors are 1 and itself. The first few prime numbers are 23, 5, 7, 11, 13, 17, 19, 23, and 29. (Source)

A composite number is a positive integer that has factors other than just 1 and the number itself. For example, 4, 6, 8, 9, 10, 12, etc. are all composite numbers. The number 1 is not composite (nor prime) (Source: Math

Activities & Games

Activity: Use a Hundred Chart to find all prime numbers up to 100 using The Sieve of Eratosthenes (scroll down just a bit to find it.) To make things easier, try this Sieve of Eratosthenes Worksheet. You could also do the activity on this one which is nice because you can write the definitions of prime/composite numbers on it as well, so it's awesome for notebooking-it just doesn't include the instructions.) Also Prime Number Hunter from

Activity:  I like to have my kids memorize the first 10 prime numbers or so as it will be useful for prime factorization (which we also use to simplify fractions).

My Prime/Composite/Prime Factorization Pinterest Board