📐 Sides and Corners: Let’s Count Shapes

Hello! Today we will count the sides and corners of shapes. Then we will look at objects from everyday life too.

Let’s look at the triangle first. A side is a straight line of a shape. Let’s count: 1, 2, 3 sides. A corner is where two sides meet. Let’s count: 1, 2, 3 corners. A triangle has 3 sides and 3 corners.

Now the square and the rectangle. Both have 4 sides and 4 corners. All four sides of a square are the same length. The opposite sides of a rectangle are equal: two sides are long and two sides are short.

This is a pentagon. Let’s count its sides and corners. Did you notice? A triangle has 3, a square has 4, a pentagon has 5. In every shape, the number of sides is the same as the number of corners!

The circle is different! On a triangle your finger gets stuck on the corners. On a circle your finger glides round, because a circle has no corners. It has no straight sides either, just one curved edge.

Now let’s look at 3D shapes. A dice is a cube. A tea box is a cuboid. A tin is a cylinder. A ball is a sphere. The faces of a dice are squares. The top and bottom of a tin are circles. A ball has no flat faces at all.

Which ones roll? Let’s put them on a sloping board. The ball rolls. The tin lying on its side rolls too. The dice and the tea box stay where they are, because they have flat faces.

Now let’s stack them up! The dice, the tea box and the tin stay put on their flat faces. And what about the ball? The ball rolls off and falls!

Summary: a triangle has 3 sides and corners, a square and a rectangle have 4, a pentagon has 5. A circle has no corners. A cube and a cuboid stay put on their flat faces. A cylinder rolls when it lies on its side, and a sphere always rolls. Now try it in Shape Workshop!