Concept 1 of 6
Flat Shapes
Today's big idea
Name a flat shape by its outline: count its sides.
4 equal sides is a square; 3 sides is a triangle.
How it works
👀 What's going on?
A door, a wheel, a slice of pizza. Every flat shape has a name.
💡 Here's the trick
Name a flat shape by its outline. A square has 4 equal sides, a rectangle has 4 sides (2 long and 2 short), a triangle has 3 sides, and a circle is round with none.
4 equal sides is a square. 3 sides is a triangle. Round with no sides is a circle.
✍️ Try it
A shape has 4 sides, two long and two short. What is it? → rectangle.
⚠️ Watch out
A circle has no sides and no corners, but it is still a shape.
Watch me solve one
Quanta solves it
“Watch how I think through one of these — then you try.”
THE PROBLEM
“A shape has 4 sides, two long and two short. What is it?”
- 1
Count the sides
It has 4 sides.
- 2
Look at the lengths
Two long and two short, not all equal.
- 3
Name it
4 sides, 2 long and 2 short is a rectangle.
- 4
Answer ✓
rectangle
Now you try one — same steps, different story 👇
See it in action
⚡ Time to play!
Look at the outline. Tap the shape’s name.
Quick check
✅ VERIFICATION
Which shape has exactly 3 sides?
⚡ Finish the activity above first to answer.
Keep going!
Up next: Sides & Corners
A pentagon has 5 sides; a hexagon has 6.