🦘 Kangaroo Grade 3 · session 6 of 24 · 60 minutes · ⭐ Plus

Counting squares, triangles and shapes

How many squares are on a chessboard? Not 64! Count shapes by size, never one by one, and the big questions become short sums.

⭐ Unlock with Plus

A complete lesson · 60 minutes

Teach it, see it, practise it, all on this page.

Open this page with your learner and work down it, or press Teach this lesson to go through it one step at a time on a big screen. Every section has something to do.

  1. Warm-up4 min
  2. Squares8 min
  3. Rectangles9 min
  4. Triangles7 min
  5. Pairs7 min
  6. Activity 17 min
  7. Activity 27 min
  8. Activity 36 min
  9. Quiz4 min
  10. Set the project1 min

By the end you can

  • Count all the squares in a grid size by size
  • Count rectangles and segments in a strip
  • Count triangles in fan figures
  • Count handshakes and lines without missing any

Before you start

  • Adding small numbers quickly
  • Square numbers (1, 4, 9, 16, …) help

Have ready

  • Squared paper
  • Coloured pencils

Grade 3 · ages 8 to 9 · contest level 3–4

Warm-up · think first

How many squares are on a chessboard? Most people say 64. Is that all of them?

Show the answer

No. There are 204 squares: 64 small ones and also 2 by 2, 3 by 3, … up to the whole 8 by 8 board. You will be able to count them by the end of the lesson.

Teacher tip: Take a few guesses and write them down. Come back to them at the end of part 1.

More warm-ups for every class →

Part 1 of 4 · learn, see, practise

Squares in a grid

Count squares one size at a time. In a 3 by 3 grid there are 9 small squares, 4 squares of size 2 by 2 and 1 big 3 by 3 square: 14 altogether.

In an n by n grid there are n × n small squares, then (n − 1) × (n − 1) squares of the next size, and so on down to 1.

Example 1

How many squares of any size are in a 3 by 3 grid?

  1. 1 by 1: 9.
  2. 2 by 2: 4 (the top-left corner of one can be in 2 rows and 2 columns).
  3. 3 by 3: 1. Total 9 + 4 + 1 = 14.

Answer: 14

Example 2

How many squares are in a grid 2 squares tall and 4 squares wide?

  1. 1 by 1: 8.
  2. 2 by 2: 3 (they fit in 3 positions along the row).
  3. 8 + 3 = 11.

Answer: 11

Square finder

Choose the grid size and the square size. Every square of that size is outlined in turn and counted.

  1. Count all the squares in a 4 by 4 grid.
  2. Show the 2 by 2 squares in a 5 by 5 grid.
  3. Find the grid that has exactly 55 squares.

Practise it

Start with the warm-up and go as far as you can. The stretch questions are meant to be hard.

Warm-up

Warm-up

Core

Core

Stretch 🔥

Stretch 🔥

Answers (for the teacher)
  1. 16
  2. 5
  3. 9
  4. 30
  5. 26
  6. 204

⭐ Part of Pure Faith Plus

The rest of this lesson is in Plus

You have seen the plan, the warm-up and part 1. With Plus you also get:

  • Part 2: Rectangles in a strip, with practice at three levels
  • Part 3: Triangles in figures, with practice at three levels
  • Part 4: Count without missing any, with practice at three levels
  • Class activity 1: Grid square hunt
  • Class activity 2: Rectangle count
  • Class activity 3: Tournament planner
  • A 8-question quiz
  • After-class project: Shape hunt poster
  • Homework and a printable practice sheet with answers
  • Teach mode and the minute-by-minute teacher's plan

The first 2 lessons of every course, every game and all maths practice stay free.

That is ₹208 a month for every lesson of every course. Prefer a teacher? Ask about live classes.

FAQ

Counting squares, triangles and shapes: questions

How many squares are on a chessboard?

204: 64 + 49 + 36 + 25 + 16 + 9 + 4 + 1, counting every size from 1 by 1 to 8 by 8.

How do you count triangles in a figure?

Find triangles that share a corner and count the pieces of the opposite side like a strip: 3 pieces give 3 + 2 + 1 = 6.

Why are counting questions hard in Math Kangaroo?

It is easy to miss the bigger shapes. Counting one size at a time, and writing each size down, fixes that.

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