Lines, rays and angles in shapes
Knowing the names for lines, rays, and angles gives your child the building blocks of geometry, and they will use them in every grade that follows. They make it possible to describe a shape exactly, to follow the wording of later problems, and to sort shapes by their features, which comes next. In 5th grade your child uses them to group shapes into families, and in middle school to work with angles, lines, and figures on a graph.
In this video, your child will learn to name rays, angles and kinds of lines.
The lesson stops at each question for your child's answer.
Three problems, each a little harder
Each problem is worked step by step. Your child will solve the last one before Bobby shows how.
Example 1
How many right angles does this shape have?
Example 2
How many pairs of parallel sides does this shape have?
Your child's turn
How many pairs of parallel sides does this shape have?
The three key steps
- 1Right angle: a square corner
- 2Perpendicular sides: right angle
- 3Parallel sides never meet.
Mistakes to listen for
- Mixing up lines, rays, and segments, such as calling a segment with two endpoints a line.
- Calling an angle obtuse because its rays are long, or acute because they are short, instead of checking how wide it opens.
- Thinking perpendicular lines must run straight up and across, and missing them when they are tilted on the page.
The lesson shows every step, so your child sees why it works. Read our parent's guide to spotting lines, rays, angles, and parallel lines →
Is your child ready to practice what they've learned?
Bobby's Math Club offers unlimited practice for free.
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More 4th grade Geometry, with questions your child answers along the way.
Questions parents ask
Does my child need an account to watch?
No. You can watch this on any device at any time. If your child would like to practice spotting lines, rays, angles, and parallel lines, and you'd like parent-friendly reports on your child's progress and growth, you can join Bobby's Math Club for unlimited free practice.
What happens when my child answers a question?
A right answer gets a cheer, and the lesson carries on. If your child isn't sure, they can tap "I don't know yet", and Bobby gives the answer and shows another example. Nothing is scored or stored.
Is this the same lesson that's on YouTube?
Yes. Here, the lesson stops at each question and waits for your child to answer. On YouTube, each question stays on screen for a few seconds, and then the lesson plays on.
Where can I learn more?
There's a short, kid-friendly lesson like this one for every Pre-K to 5th grade math skill, all in our video library. Our parent's guide to spotting lines, rays, angles, and parallel lines has more on where kids get stuck and how you can help at home. In the club, your child practices at just the right level, about five minutes a day, and you get parent-friendly reports as they grow. Learn more about how it works →
Practice spotting lines, rays, angles, and parallel lines
Questions at your child's level, about five minutes a day, on spotting lines, rays, angles, and parallel lines and whatever PK-5 skills they need to develop. Unlimited practice, free forever.
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