Spark CoachBuild Expeditions
Skills
MathOn grade · 11 min3.MD.C.7

Area and Perimeter

Area tells you how much stuff you need to COVER something; perimeter tells you how much you need to go AROUND it — and buying the wrong one is how a project runs out of tile.

The idea

Area is the space inside. Cover the shape with unit squares and count them: rows times columns. Perimeter is the distance around the edge — walk all four sides and add them up. Same rectangle, two very different questions.

Think it through

Ivy is tiling a garden bed with square tiles. She lays 4 rows with 6 tiles in each row, and the tiles cover it completely. What is the area of the garden bed in square tiles?

That same garden bed is 6 feet long and 4 feet wide. Ivy wants to put a wooden edge all the way around it. How many feet of wood does she need?

Sam's rug is made of square patches sewn together: 3 rows with 7 patches in each row. What is the area of the rug in square patches?

A bulletin board is 9 feet long and 5 feet wide. Priya is taping a ribbon along every edge, all the way around. How many feet of ribbon does she need?

Work all the way through to finish. 3 of 4 right and it’s hers.