Same Perimeter, Different Area

Compare rectangles with the same perimeter or the same area.

Warm-up, learn, try it together, practice, then a quick check. About 15 minutes.

What children learn in Level 77

Here's a puppy pen made of 18 fence panels. It's long and thin, with only 8 squares of grass inside.
The same 18 panels can make a different pen. This one is 3 by 6, with 18 squares inside! Same perimeter, different area.
Your turn! Change the sides to use all 18 panels and give the puppy the most room inside.
4 by 5 holds 20 squares, the most! With the same fence, pens closer to a square hold more.
It works the other way too. 12 squares as 2 by 6 needs 16 panels, but 3 by 4 needs only 14. Same area, different perimeter.

Georgia's K-12 Mathematics Standards:

3.GSR.8.2 — Investigate and describe how rectangles with the same perimeter can have different areas or how rectangles with the same area can have different perimeters.