Students will learn two methods for identifying common factors. The first, is to list all the factors of both numbers, then identify which factors are common. The second, is to find the prime factorization of both numbers, then identify which prime factors are common, then use combinations of those factors to determine the common factors of the two original numbers.

How to Find Common Factors from Prime Factorization by Anil Kumar

Next, give your students these challenges:

- Routes 1 and 5 by NRICH
- The Brown Family by NRICH

Conclude by leading this investigation:

Pin Board Murders (patterns, angles, discussion)

by MathPickle