Saturday, September 11, 2021

Rabbits in a Pen: Area and Perimeter

 Recently, I finished my master's degree in elementary math education with a certification as a Math Specialist. I learned a lot and hope to put in the next steps necessary to put the information to use in my classroom and grade level. 

One of the problems introduced in my Geometry class was called Rabbit and Pen.  (Credit unknown but will name Dr. Webel for sharing it.) This problem opens the door for so many concepts to emerge!

  • Perimeter
  • Area
  • Counting for Area
  • Multiplying for Area
  • Perimeter and Area are not necessarily equal
I encourage teachers to share the problem with some tools for students to explore. If you have large Geoboards, a Geoboard app (found here), or graph paper for students to model their thinking on.

Here is the student version that I made here.  While I thought I retained the images from the whiteboard app that the students created, I apparently did not save them! However, I want to provide a visual of the work that shows the types of models that the kids created that sparked our discussion.


This activity reveals to students that while the perimeter is “fixed” (you have the same amount of fence to use, like 16 ft)  the dimensions produce a different area. The students might also realize that there is a method to making sure they have all of the different combinations possible. If they are not methodical, you could ask how they know they have thought of all of the possible ways to make the most space for the animals? I hope students would ask or wonder if they used a square (and squared numbers) would that always give you the most space? This lesson certainly lays the groundwork for students to wonder if this is a possibility.

16

20

10

1, 7

1, 9

1, 4

2, 6

2, 8

2, 3

3, 5

3,7


4, 4

4, 6



5, 5