4th Grade Types of Angles Worksheet (Acute, Right, Obtuse)
Look at each angle and tell whether it is acute (less than a right angle), right, or obtuse (more than a right angle).
- Homework
- Centers
- Review
- Test Prep
Download the Free Printable PDF
No sign-up required. Clean, low-ink US Letter format.
- Grade
- 4th Grade
- Subject
- Math
- Skill
- Geometry
- Topic
- classifying angles as acute, right, or obtuse
- Difficulty
- Standard
- Time
- 12 minutes
- Pages
- 2 (incl. answer key)
- Format
- Printable PDF (US Letter)
- Answer key
- Included
- Best for
- homework, centers, review, test prep
Worksheet details
What This Worksheet Practices
Students will classify angles as acute, right, or obtuse by comparing them to a right angle.
- Recognizing a right angle (90 degrees)
- Classifying acute and obtuse angles
- Comparing an angle to a right angle
Inside This Printable
Student directions: Write whether each angle is acute, right, or obtuse. Compare each one to a right angle (a square corner).
Worked example
An angle that opens exactly like a square corner is a right angle (90 degrees).
Sample questions
- Acute, right, or obtuse?
- Acute, right, or obtuse?
- Acute, right, or obtuse?
The PDF contains 6 practice questions plus 2 challenge questions.
Worksheet Preview
Compare every angle to a right angle
The easiest way to classify an angle is to compare it to a right angle — the square corner that measures 90 degrees. A smaller opening is acute; a wider opening is obtuse; an exact square corner is right. A common trap: the length of the rays doesn’t matter, only how wide the angle opens.
How to use it
Have students picture a square corner and ask, “Is this opening smaller, the same, or wider?” That single comparison sorts every angle. Builds on recognizing 2D shapes and their corners.
👩🏫 Teacher note
Compare every angle to a right angle (a square corner). Smaller opening = acute; square corner = right; wider opening = obtuse. The length of the rays does not matter.
🏠 Parent note
A right angle looks like the corner of a square. Smaller than that is acute; wider is obtuse.
Common Mistakes to Watch For
- Confusing acute and obtuse
- Judging by ray length instead of the opening
Answer Key
Each answer says acute, right, or obtuse.
⬇ Download Answer Key (PDF)Learn this skill first
Take the free lesson on geometry — worked examples and practice exercises, then come back to this worksheet.
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