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🔺 4th grade math · Shapes & Space

Angles, triangles, symmetry

A right angle is a square corner, 90 degrees. Acute is smaller. Obtuse is bigger, up to a straight line.

Worked example

What kind of angle is this? (Compare it to a square corner.)
Answer: obtuse
An obtuse angle is bigger than a right angle but smaller than a straight line.

For grown-ups: Classify by lines and angles; line symmetry. Below: three problems to try with the worked answers, and a free printable sheet. Children can practise the same skill as a game, with no sign-up and no ads.

  • CCSS 4.G.A.2–3
What this practises, for teachers

Practices classify by lines and angles; line symmetry (4.G.A.2–3). A printable sheet with its answer key, worked answers on the page, no accounts.

▶ Practise it

For your class

🖨️ Printable sheet and key

On the board with this skill:

Try three

  1. What kind of angle is this? (Compare it to a square corner.)
    Show the answer and how
    Answer: obtuse
    An obtuse angle is bigger than a right angle but smaller than a straight line.
  2. What kind of angle is this? (Compare it to a square corner.)
    Show the answer and how
    Answer: obtuse
    An obtuse angle is bigger than a right angle but smaller than a straight line.
  3. What kind of angle is this? (Compare it to a square corner.)
    Show the answer and how
    Answer: obtuse
    An obtuse angle is bigger than a right angle but smaller than a straight line.

Before and after

Learn first: Lines, rays and angles (4th)

Comes next: Dots on a grid (5th)

Name: ____________________Date: ____________Score: ____ / 12

Angles, triangles, symmetry (4th grade)

  1. What kind of angle is this? (Compare it to a square corner.)
  2. What kind of angle is this? (Compare it to a square corner.)
  3. What kind of angle is this? (Compare it to a square corner.)
  4. What kind of angle is this? (Compare it to a square corner.)
  5. What kind of angle is this? (Compare it to a square corner.)
  6. What kind of angle is this? (Compare it to a square corner.)
  7. What kind of angle is this? (Compare it to a square corner.)
  8. What kind of angle is this? (Compare it to a square corner.)
  9. What kind of angle is this? (Compare it to a square corner.)
  10. What kind of angle is this? (Compare it to a square corner.)
  11. What kind of angle is this? (Compare it to a square corner.)
  12. What kind of angle is this? (Compare it to a square corner.)

Answer key

  1. acute
  2. right
  3. right
  4. acute
  5. right
  6. right
  7. obtuse
  8. acute
  9. straight
  10. acute
  11. straight
  12. acute

More 4th grade skills: all 4th grade math skills, or every grade at math skills.