Eureka Math Grade 4, Module 4: Angle Measure and Plane Figures
In this unit, your child learns the language of geometry and how to measure angles. They draw lines, rays, and angles; spot parallel and perpendicular lines; measure and draw angles with a protractor; and find missing angles. They also sort triangles and quadrilaterals and find lines of symmetry. It follows the multiplication unit and leads into fractions.
By Robert “Bobby” BarnettMath teacher, parent, and founder of Bobby’s Math Club
What is my child learning in Module 4?
- Recognizing that an angle turns through part of a circle, so 90 degrees is a quarter turn and 180 degrees a half turn. Learn more: What angles are and how degrees measure them
- Measuring angles to the nearest degree with a protractor, first estimating against a right angle to read the right scale. Learn more: Measuring and drawing angles with a protractor
- Finding missing angles around a point or along a straight line, using the fact that they add to 360 or 180 degrees. Learn more: Adding angles together to find a missing one
- Drawing points, lines, segments, rays, and angles, and identifying parallel and perpendicular lines in figures. Learn more: Spotting lines, rays, angles, and parallel lines
- Classifying triangles as right, acute, or obtuse, and quadrilaterals by their parallel and perpendicular sides. Learn more: Sorting shapes by their sides and angles
- Recognizing line-symmetric figures and drawing every line of symmetry, like the four on a square. Learn more: Finding lines of symmetry
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
- Make angles with two pencils joined at one end. Ask your child to make a small angle and a big one, then swap in longer pencils and see whether the angle changes.
- Cut a paper plate into slices of different sizes. Put two slices side by side and ask how the angle at the center of both together compares with each one.
- Look for shapes on road signs during a walk or ride. Ask your child which have parallel sides and which have right angles, like a rectangular speed limit sign.
Where kids can get stuck
- Missing a right triangle because it is turned so the square corner isn't at the bottom.
- Adding the parts and the whole angle together, giving 150 degrees for an angle made of 30 and 45.
- Stopping after one line of symmetry on a shape with several, like a square.
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 made by two rays that share an endpoint.
- 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.
- ray
- A part of a line that starts at one point and goes on forever in one direction.
- parallel lines
- Lines that always stay the same distance apart and never meet.
- perpendicular lines
- Lines that meet or cross to make right 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.
- line of symmetry
- A line that folds a shape into two halves that match exactly.
Ready to build your child’s confidence with angles and plane shapes?
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 Eureka Math Grade 4 Module 4 cover?
Eureka Math Grade 4 Module 4 covers these math standards. Each one links to what it means, sample questions, and teaching strategies.
- 4.MD.C.5: Understand angles as turns measured in degrees: a full turn is 360°.
- 4.MD.C.6: Measure angles in degrees with a protractor.
- 4.MD.C.7: Add angles together, and find a missing angle.
- 4.G.A.1: Name rays and angles, and spot parallel and perpendicular lines.
- 4.G.A.2: Sort shapes by their parallel sides and right angles.
- 4.G.A.3: Find lines of symmetry, where a shape folds into matching halves.
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.