MA.3.GR.2.2: Find the area of a rectangle with whole-number side lengths using a…

Fence It, Fill It: Area and Perimeter Grades 3–4

Which mat is really the biggest? Does the same fence always hold the same garden? Can the same rug need more edging? Four lessons where students tile, stretch rope and chalk the schoolyard to find out that area and perimeter measure different things.

• Which mat is the biggest? 50–60 min

  Teams cover three taped mats with sticky notes and find that the long, thin mat that looks biggest is the same size as a small square one. Students explain area as the number of unit squares that cover a shape, and find it faster by multiplying rows by columns.

• Does the same fence always hold the same garden? 50–60 min

  Teams stretch the same 12 m rope loop into different rectangles in the schoolyard and find that a fence of the same length can hold 5, 8 or 9 square metres. Students find perimeter by adding the sides, find area by multiplying, and recommend a shape for a school garden.

• Can the same rug need more edging? 45–60 min

  Teams build every rectangle they can from the same 24 square tiles and find that the edging around them runs from 20 to 50 tile edges. Students explain that the same area can have different perimeters, and use length × width = area to find a missing side.