This can be used as a center or an introduction. My kids love anything that deals with food so this was great. I used this to review area and perimeter and I changed the measurement of each cracker to change up the dimensions. I use the first page to show how they are going to do this and then you can either make multiple copies. I color code my cards and have one for each student or you can cut them apart and have the kids get up to get them moving.