Illustrative Mathematics Grade 4, Unit 7: Angles and Angle Measurement
In this unit, your child learns about points, lines, rays, and angles, and how angles are measured. They see an angle as a turn measured in degrees, use a protractor to measure and draw angles, and add angles to find unknown measures. It follows the multiplying and dividing unit and leads into sorting two-dimensional shapes.
By Robert “Bobby” BarnettMath teacher, parent, and founder of Bobby’s Math Club
What is my child learning in Unit 7?
- Measuring angles by how far a ray turns, with the help of a clock face or a circle split into 360 degrees. Learn more: What angles are and how degrees measure them
- Estimating and then measuring angles with a protractor, and drawing angles of a given size from a ray. Learn more: Measuring and drawing angles with a protractor
- Finding unknown angles that combine with known ones to make 90, 180, or 360 degrees. Learn more: Adding angles together to find a missing one
- Drawing points, lines, rays, and segments, and naming right, acute, and obtuse angles. Learn more: Spotting lines, rays, angles, and parallel lines
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
- Watch the minute hand on a clock. Ask how many degrees it turns in 15 minutes, 30 minutes, and an hour, and how your child figured it out.
- Make angles with two chopsticks or pencils joined at one end. Ask your child to show a right, an acute, and an obtuse angle, then guess each one in degrees.
- Fold the corner of a sheet of paper so it splits into two angles. Measure one part, about 30 degrees, and have your child predict the other, about 60.
Where kids can get stuck
- Thinking an angle with longer rays is bigger, even when both angles open the same amount.
- Placing the protractor's corner at the vertex instead of its center mark, so every reading is off.
- Using 180 instead of 90 as the total when finding a missing part of a right angle.
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
- point
- An exact spot, shown with a dot and named with a capital letter.
- ray
- A part of a line that starts at one point and goes on forever in one direction.
- line segment
- A part of a line with two endpoints.
- angle
- The figure made by two rays that share an endpoint.
- vertex
- The point where two rays or two sides meet.
- degree
- The unit for measuring angles; a full turn is 360 degrees.
- protractor
- A half-circle tool marked in degrees, used to measure and draw angles.
- acute angle
- An angle smaller than a right angle, measuring less than 90 degrees.
- obtuse angle
- An angle larger than a right angle but smaller than 180 degrees.
Want to help your child master angles and degrees?
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.
Join the club
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 Illustrative Mathematics Grade 4 Unit 7 cover?
Illustrative Mathematics Grade 4 Unit 7 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.