KShapesK.G.B.4

Sides and Corners

Compare shapes by counting their sides and corners.

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You know flat shapes and you can count. Counting sides and corners helps you name and compare shapes.

The gold dots mark the corners.

Key idea

A side is a straight edge. A corner is where two sides meet. A shape with straight sides has the same number of sides and corners.

Why it works

Each side ends at a corner, and the next side starts there. Going around the shape, you meet one corner after each side, so the numbers match.

Worked example: A hexagon

How many sides and corners does a hexagon have?
  1. Put a finger on one side and go around: 1, 2, 3, 4, 5, 6.
  2. It has 6 sides and 6 corners.

Answer: 6 sides and 6 corners

Drag a corner. The shape changes, but it still has 3 sides and 3 corners.
For grown-ups: Build shapes with straws or craft sticks. Count the sides and corners together.

Practice

Pass with 3 right answers, the last 2 in a row. Each right answer earns 1 XP.

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Sources and further reading

  • Common Core State Standards for Mathematics, Kindergarten, K.G.B.4: analyze and compare shapes using their parts, such as the number of sides and corners
  • Institute of Education Sciences practice guide: Teaching Math to Young Children (NCEE 2014-4005)
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