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Math · Stage 5

Find the perimeter and area of compound (composite) shapes

A compound shape is just rectangles joined together. For AREA, split it into rectangles and add — or take the whole rectangle and subtract the missing piece. For PERIMETER, work out every hidden side first, then add all the way around.

✦ Math📘 Stage 5 · S5⏱ ~13 min🧒 Ages 9–10★ Free to start
I can find the perimeter and area of compound (composite) shapes.
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Kavi the owl for Math
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Kavi Tiles the Clubhouse Floor 🧩

Kavi is tiling an L-shaped clubhouse floor 🧩. "Two jobs again," hoots Kavi. "The skirting board runs right around the edge — that's the perimeter, so I must find every hidden side first. The tiles cover the space inside — that's the area. For a funny shape I just split it into rectangles and add, or take the big rectangle and subtract the corner that isn't there!"

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What your child will learn

1Perimeter around, area inside — even for a funny shapeA compound (composite) shape is made of rectangles stuck together. It still has two different measurements. Tap each card.
2Area: split and add, or big minus holeAn L-shape is a big rectangle with a corner missing. There are two good ways to find its area — tap each part.
3Split a bigger shape, then add the areasAn L-shape splits into rectangle A = 8 × 6 = 48 cm² and rectangle B = 9 × 3 = 27 cm². Add the two areas — tap Step →.
4Perimeter: find the missing sides, then add aroundA compound shape often hides a side length you are not told. Tap each card to see the two moves.
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A peek inside

An L-shape is a 7 cm by 5 cm rectangle with a 3 cm by 2 cm corner removed. Find its area and its perimeter.
area = big − hole = 7 × 5 − 3 × 2 = 35 − 6 = 29 square cm · perimeter = 2 × (7 + 5) = 24 cm (the steps add up to the big sides)

Try this at home: An L-shape splits into a 5×4 rectangle and a 3×2 rectangle. Area = 20 + 6 = __

Ready to play and learn?

Start the free interactive lesson, or print the handout for screen-free play.

Start the free lesson →⬇ Download PDF

Part of Math · Stage 5 · S5 on KAVI Academy — a secular, whole-child learning platform for ages 5–12.