Name 2D Shapes by Sides and Corners (2nd Grade)

What is it?

A flat (2D) shape can be named by what it is made of, not by how big it is or which way it points. Sides are the straight edges, and corners are the points where two sides meet. Counting both gives a quick way to name a shape. A triangle has 3 sides and 3 corners. A square and a rectangle each have 4 sides and 4 corners. A hexagon has 6 of each. A circle is round, with no straight sides and no corners.

Step by step: 6 sides and 6 corners is a hexagon

1. Look at a shape with 6 straight sides.
2. Count the sides by touching each one: 1, 2, 3, 4, 5, 6. There are 6 sides.
3. Count the corners the same way. There are 6 corners.
4. A flat shape with 6 sides and 6 corners is a hexagon. "Hex" means six.
5. Now compare: a triangle has 3 sides, a square or rectangle has 4, and a circle has no sides at all.

Common mistakes

• Naming a shape by its position. A triangle turned upside down is still a triangle.
• Counting a side twice, or skipping one. Put a finger on the first side and move around to it again.
• Mixing up a square and a rectangle. Both have 4 sides and 4 corners, but a square has all 4 sides the same length.

Your turn

Here is a problem to try. Pause and let your child work it out before you check.

A shape has 3 sides and 3 corners. What shape is it?

Answer: A triangle. Any flat shape with 3 straight sides and 3 corners is a triangle, no matter its size or which way it points.

Practice at home

Go on a shape hunt around the house: a window, a plate, a slice of pizza, a stop sign. Have your child count the sides and corners before they name each one. Then draw a shape with a given number of sides, like 4 or 6, and compare drawings.