Geometry — shapes and perimeter

In Grade 2 you sorted shapes and counted their sides. This year you take three new steps:

• Classify polygons by the number of sides — triangle, quadrilateral, pentagon, hexagon.
• Find right angles — the corners that look like the corner of a sheet of paper.
• Identify lines of symmetry.
• Compute perimeter — the distance all the way around a shape.

What you'll learn

• Classifying polygons — name shapes by sides.
• Right angles — find them in shapes.
• Symmetry — fold to find a matching half.
• Perimeter — add the sides.
• For parents — how to help at home.

Try it

• 🔷 Classify polygons
• ⊥ Right angles
• 🪞 Symmetry
• ▭ Rectangle perimeter
• 🔺 Triangle perimeter

Summary

• Polygons get their names from their side count.
• A right angle is a 90° corner.
• A line of symmetry folds the shape in half so the parts overlap.
• Perimeter = sum of all sides.

Classifying polygons →