Reveal Math Grade 4, Unit 11: Angles
In this unit, your child learns that an angle is measured in degrees as a turn through part of a circle, uses a protractor to measure and draw angles, and adds and subtracts angle measures to find unknown angles. It builds on naming angles in the geometry unit and leads into a unit on measurement.
By Robert “Bobby” BarnettMath teacher, parent, and founder of Bobby’s Math Club
What is my child learning in Unit 11?
- Seeing an angle as part of a circle, so a quarter turn is 90 degrees, a half turn is 180, and a full turn is 360. Learn more: What angles are and how degrees measure them
- Lining up a protractor's center point and baseline to measure angles to the nearest degree, and sketching angles of a given size. Learn more: Measuring and drawing angles with a protractor
- Finding an unknown angle by adding or subtracting, such as the missing part of a straight angle when one part is 115 degrees. Learn more: Adding angles together to find a missing one
Sample questions to try together
These are real questions from our practice. Tap the speaker to hear one read aloud, or the light bulb for a hint, and talk about the answer together.
Question 1 of 3
An angle measures 60°. How many one-degree angles does it turn through?
- 300
- 60
- 6
How you can help
- Use a clock: ask your child what angle the hands make at 3:00 and at 6:00, then how many degrees the minute hand turns in 15 minutes.
- Do turns while you walk: face forward, make a quarter turn, then a half turn, and ask your child how many degrees you have turned in all.
- Open a book partway, estimate the angle together, then ask what size the other angle would be to make a straight line.
Where kids can get stuck
- Measuring an angle with a ruler in inches, as if the length of the rays decided its size.
- Guessing a reading when a ray is too short to reach the protractor's scale, instead of drawing it longer.
- Adding the parts and then the whole angle too, so an angle made of 30 and 45 degrees seems to measure 150.
Practice makes perfect
Bobby's Math Club has practice problems that adapt to your child’s level, each with a detailed explanation and an easy-to-follow video, so your child can build confidence in these skills one step at a time.
Words your child will hear
- angle
- The figure formed where two rays meet at the same endpoint.
- vertex
- The point where the two rays of an angle meet.
- ray
- Part of a line with one endpoint that goes on forever in one direction.
- degree
- The unit for measuring angles; a full turn is 360 degrees.
- protractor
- A tool for measuring and drawing angles in degrees.
- right angle
- An angle that measures exactly 90 degrees, like the corner of a sheet of paper.
- straight angle
- An angle that measures 180 degrees and looks like a straight line.
- acute angle
- An angle smaller than a right angle, less than 90 degrees.
- obtuse angle
- An angle wider than a right angle but less than 180 degrees.
Want to help your child master measuring angles?
In Bobby's Math Club, your child practices these skills at just the right level, with a hint when they need one, a clear explanation after every question, and kid-friendly videos. Unlimited practice is free.
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Written by Robert “Bobby” Barnett
Bobby is an award-winning math teacher, the author of Meet Every Learner’s Needs, and the father of two elementary-school math learners. He uses Bobby’s Math Club with his own kids a few times every week. Learn more or contact Bobby.
Which math standards does Reveal Math Grade 4 Unit 11 cover?
Reveal Math Grade 4 Unit 11 covers these math standards. Each one links to what it means, sample questions, and teaching strategies.
For teachers: Unit names and order vary between editions and districts, so your school’s own materials have the exact sequence. Learn how Bobby's Math Club can help your students grow.