I had only 5 geoboards so when I was teaching them how to do perimeter on them, I had them in small groups. One student made a random shape on their board (I set the rule that it had to be straight sides and no diagonals) and then the rest of the group had to figure out the perimeter. Then they switched and that person made a shape while the others figured out the perimeter.
|For example: This one has 5 line segments across the top/bottom, and 6 on each side. Therefore 5+5+6+6= 22|
|For example: This one has 10 line segments across the top/bottom, and 5 on each side. Therefore 10+10+5+5=30|