Look around the room. A window is one shape. A clock on the wall is another. A slice of pizza, cut on the diagonal, is another shape again. Every one of these has a name — and today you are going to learn four of them: circle, triangle, square and rectangle.
To name a flat shape we look at two things: its sides — the straight edges you
could trace with your finger — and its corners — the pointy bits where two
sides bump into each other. You already know how to
Cut a piece of toast across the middle, corner to corner, and one half makes a triangle. So does a slice of pizza, and so does a road sign that warns "danger ahead". A triangle always has exactly 3 straight sides and 3 corners — never more, never fewer. Trace one with your finger: side, corner, side, corner, side, corner. Three of each.
A door is a shape with 4 straight sides and 4 corners, and every one of its corners is a neat, square corner — like the corner of a book. That makes it a rectangle. Look closely, though: two of its sides are long and two are short.
A square is a rectangle's tidier cousin. It also has 4 straight sides and 4 square corners — but a square's sides are all exactly the same length. A window pane that is just as tall as it is wide is a square; a door, taller than it is wide, is a rectangle. Same number of sides and corners, but look at the lengths to tell them apart.
Not because it's small — because all four of its sides match. You could draw a giant square bigger than a tiny rectangle, and it would still be a square. The difference between a square and a rectangle is never about size — it's about whether all four sides are the same length (square) or come in two long sides and two short sides (rectangle).
A clock face is round. So is a wheel, a coin, and the biscuit on a plate. A circle is the odd one out of our four shapes: it is one smooth, curved line with no straight sides at all and no corners to trace. Run your finger round a circle and it never once changes direction sharply — it just keeps curving.
That is exactly why wheels are round and not square: a circle has no corners to bump and judder over, so it rolls along smoothly.
Step through the gallery below to meet all four shapes, one at a time. Read the caption under each one, then count its sides and corners for yourself before you move on.
Before you press Refresh, say the shape's name out loud — is it a circle, a triangle, a square or a rectangle? Then check yourself against the label.
Size and colour never change a shape's name. A tiny red triangle and a huge blue triangle are both still triangles — what matters is the count of straight sides and corners, not how big the shape is or what colour it's coloured in. And remember: a square and a rectangle both have 4 sides and 4 corners — don't tell them apart by size, tell them apart by whether all four sides match (square) or only the opposite pairs match (rectangle).
One day you'll meet shapes with even more sides — five, six, eight — and learn their proper
family names, like "polygon" and "quadrilateral", in