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What makes a shape that shape

Counting sides and corners, and using them to name a shape.

Paper packet. Every task here also exists on screen, where it is checked automatically; answers written on paper are not assessed by Nydus. When you are back at a device, enter your answers there.

1. What you will learn

In this lesson you count the sides and corners of a shape, and use them to say what it is.

2. Get ready

Find a flat triangle or draw one. Point around its edge instead of counting the space inside.

3. Shape words

4. Follow the edge

A side is a straight piece of a flat shape's boundary. A corner is where two sides meet. Trace one side with a finger, then stop at the corner. A triangle has three sides and three corners. The boundary joins up; there is no gap.

Another way: picture

Compare the triangle's straight sides with the circle's curved outline.

5. Turn it and check

Turn a square so one corner points up. It still has four equal sides and four square corners. Turning does not change its name. A rectangle also has four sides and square corners; its sides need not all be equal. A circle curves all the way around and has no corners. Count the boundary features, not the color or the direction a shape points.

6. Count a triangle's sides.

1. Mark a starting corner.

   Trace sides 1 and 2

   The mark helps avoid counting twice.

2. Return along the last side.

   3 sides

   Now every straight edge has been counted once.

7. Turn a square. Count its corners.

1. Point at every turn.

   1, 2, 3, 4

   The corners move but do not disappear.

2. Your turn: work this step out. Its working is at the end of the packet.

   Keep the same count.

8. Guided practice

Look at the triangle. How many straight sides? 

Answer:

Audio transcript: None

9. Guided practice

A cutout has three straight sides and three corners. Which shape is it?

• triangle
• square
• circle

Audio transcript: None

10. Practice

A square tile has a corner at each turn. How many corners?

Answer:

Audio transcript: None

11. Somewhere new

A round plate turns smoothly all the way around its outline. Which description fits?

• A circle with no corners
• A triangle with three corners
• A square turned sideways

Audio transcript: None

12. Lesson test

Lesson test: one question per skill, one attempt each, no hints. Your answers are checked when you submit.

13. Test question

Record the square's boundary features. 

Straight sides: _s. Corners: _c.

Audio transcript: None

14. What you can do now

You can name a shape by counting its sides and corners. How many sides does a triangle have?

Working for the steps left to you

7. Turn a square. Count its corners., step 2