Prime and Composite Numbers

In Unit 3 of Everyday Math, we have been practicing multiplication and division.  We've used fact triangles to look at the relationship between these two operations.  Practicing division brought up many new concepts such as factors and multiples.  When finding factors, some students noticed that some numbers only have 1 and themselves as factors.  We took a detour away from our math journals and did an activity to learn more about prime and composite numbers.  


To start, the students were given a table with several numbers.  Their job was to come up with a list of factor pairs and then decide if the number was prime or composite.  After, they chose one of each type of number and drew arrays on centimeter grid paper.  Next, they cut out the arrays and glued them onto construction paper.  We used these as a display on our giant classroom bulletin board.