Explore · Mathematics · Geometry

Comparing 2-D and 3-D shapes

Analyse and compare 2-D and 3-D shapes using informal language to describe sides, vertices, and other attributes

ages 5 to 68 practice questionsvideo included

What a learner can do afterwards

Count the sides and corners of a shape
Compare a triangle and a rectangle by number of sides
Describe a cube as having 'square faces' and 'corners'

1 · Read

Every shape has sides and corners you can count. A side is a straight edge. A corner is where two sides meet.

This triangle has 3 sides and 3 corners.

Try it together

A triangle has 3 sides and 3 corners. A rectangle has 4 sides and 4 corners. The rectangle has one more side than the triangle.

Some shapes are not flat. A cube is a solid you can pick up, like a dice. Each flat face of a cube is a square. So each face has 4 straight sides and 4 corners. A cube has sharp corners you can feel with your fingers.

Every flat face on this cube is a square. Count its sides and corners the same way: 4 and 4.

Count sides and corners to tell shapes apart.

2 · Watch

3 · Play

step 1 of 6

Last time you named the flat shapes around the playground. Today you check them. Mia puts her hand on the big triangle on the climbing frame.

Mia slides her hand all the way round the triangle. How many straight sides does she slide along?

Take it off screen

Print a worksheetA4 with an answer key page for grown-ups. No screen, no internet.

Where it sits

Learn first

2-D shapes 3-D shapes

This opens up

Building & Drawing Shapes Defining attributes of shapes Edges, vertices, and faces 2-D shapes (age 6+)Combining Simple Shapes

Where this leads

Jobs that lean on this skill. Follow one to see everything it is built on.

Interior Designer Air Traffic Controller Artist Cartographer Civil Engineer Graphic Designer

Then practise

8 questions wait behind this lesson, each with its answer explained. Every answer feeds the sky: stars light as they are learned, and dim when it is time to come back.

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