Flat and solid shapes
A ball is a sphere, not a circle, and telling the two apart helps your child describe the world accurately. It prepares them to see that solid shapes are made of flat faces, like the six squares on a cube. That idea leads to building and describing both kinds of shape in 1st and 2nd grade, and much later to finding the volume of a box in 5th grade.
In this video, your child will learn to tell flat shapes from solid shapes.
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
Which shape is solid?
Example 2
Which shape is solid?
Your child's turn
Which shape is flat?
The two key steps
- 1A flat shape is thin, like paper.
- 2A solid shape is thick, like a block or a ball.
Mistakes to listen for
- Calling a ball a circle or a block a square, using a flat name because that is how it looks from one side.
- Treating a paper plate or a coin as a flat shape, not seeing that it is a very thin solid.
- Sorting shapes by color or size instead of by whether they are flat or solid.
The lesson shows every step, so your child sees why it works. Read our parent's guide to telling flat shapes from solid shapes →
Is your child ready to practice what they've learned?
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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 telling flat shapes from solid shapes, 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 telling flat shapes from solid shapes 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 telling flat shapes from solid shapes
Questions at your child's level, about five minutes a day, on telling flat shapes from solid shapes and whatever PK-5 skills they need to develop. Unlimited practice, free forever.
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