Math · Stage 6

Find area and circumference of circles; volume and surface area of solids

A circle's AREA is π × r × r and its CIRCUMFERENCE is π × d. A solid's VOLUME is the space it fills (length × width × height) and its SURFACE AREA is the total of all its faces. Take π ≈ 22/7.

✦ Math📘 Stage 6 · S6⏱ ~14 min🧒 Ages 10–12★ Free to start

I can find area and circumference of circles; volume and surface area of solids.

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Kavi Measures the Pizza and the Fish Tank 🍕

Kavi is slicing a round pizza and filling a glass fish tank 🍕🐠. "Round things and solid things each have two measurements," hoots Kavi. "A circle has an area — the flat space inside, π × r × r — and a circumference — the distance all the way around, π × d. A solid has a volume — the space it fills, length × width × height — and a surface area — the skin that wraps it, the total of its faces. Take π ≈ 22/7, and watch the units: length (cm), area (cm²), volume (cm³)."

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What your child will learn

1Space inside vs the boundary aroundCircles and solids each answer two different questions. Tap each card to see its job.

2Radius, diameter, π — and the two circle formulasEvery circle is built from its radius. Tap each part to see how the two formulas use it.

3A solid fills space and has a skinA box has a VOLUME (space inside) and a SURFACE AREA (its faces). Tap each part.

4Four measurements, their formulas and unitsTap a row to hear the formula. Take π = 22/7.

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A peek inside

A circle has a radius of 7 cm. Find its area. (take π = 22/7)

area = π × r × r = 22/7 × 7 × 7 = 22 × 7

Try this at home: A circle has radius 7 cm. Area = 22/7 × 7 × 7 = __ (take π = 22/7)

Ready to play and learn?

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

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Part of Math · Stage 6 · S6 on KAVI Academy — a secular, whole-child learning platform for ages 5–12.