Describe a Shape’s Boundary

Supplied materials

• Paper and a pencil. An adult can read aloud while you point, draw or say your answer.
• Read this example: Draw a sign with three unequal straight sides meeting at three corners. Which supplied shape fits? Supplied candidates: (A) circle (B) open zigzag (C) square (D) triangle.
• Try this question: Draw a sign with four equal sides of length two and four square corners. Which supplied shape fits? Supplied candidates: (A) circle (B) open zigzag (C) square (D) triangle.

Learn the idea

A shape is a flat area inside a closed outline. Look at its straight or curved sides and its corners. Use these features to choose a matching shape. Changing a shape’s color or name does not change its sides and corners.

Reason through the supplied case: The required boundary is three unequal straight sides meeting at three corners. A triangle has those features. The choice follows visible shape properties rather than the sign’s color or what an observer likes best.

A picture may show a shape in any size or orientation. Use the specified boundary features, and keep an open line distinct from a closed shape.

1. Ask an adult to read the sign description. Look for the number of sides and corners.
2. Explain why the sign with three straight sides and three corners matches a triangle.
3. Try the question and all three practice questions before checking their answers.
4. Make three closed outlines and label a triangle, square and circle using their boundary features.
5. Check your work: The triangle has three straight sides, the square four equal sides and square corners, and the circle a round boundary.

Check your reasoning

Your answer is temporary and is not saved to an account. Download your current answer before leaving or reloading. Written work on paper or in another app stays in your own file.

Take it further

Try one more question: Draw a sign with four equal straight sides and four square corners, rotated on the page. Which supplied shape fits? Supplied candidates: (A) circle (B) open zigzag (C) square (D) triangle. Answer: square. The required boundary is four equal straight sides and four square corners, rotated on the page. A square has those features. The choice follows visible shape properties rather than the sign’s color or what an observer likes best. Now make your own work: Make three closed outlines and label a triangle, square and circle using their boundary features. Check your work: The triangle has three straight sides, the square four equal sides and square corners, and the circle a round boundary.

Nothing here is saved to an account or sent to a teacher. The answer download includes your current choice and any checked feedback. It does not include choices from the separate More practice section. Download that section separately.