Perimeter Using Math Rods

posted Nov 15, 2018, 11:10 AM by Patrick Johnson

Students were challenged to make a rectangle out of 2 blue rods (worth 9) and 2 yellow rods (worth 5) and then find the perimeter.

Students made a variety of rectangles. They quickly discover that they couldn't just add the math rods together (9+9+5+5) to find the perimeter. For example, in the first picture below, the sides are 9 + 7 (yellow plus the equivalent of 2 whites) + 9 + 7.

We consolidated the activity by looking at some of the samples below. We discussed the reason why the 3rd sample has the greatest perimeter of all of the rectangles.