Compare flat and solid shapes
Talking about sides and corners moves your child from naming shapes to understanding them. In 1st grade they use these features to decide what makes a shape a triangle or a square, and in 2nd and 3rd grade to sort shapes by their sides and angles. Comparing shapes in words also builds the habit of explaining their thinking, which matters in every part of math.
In this video, your child will learn to compare flat and 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 has more corners, a triangle or a square?
Example 2
How many flat faces does a cube have?
Your child's turn
How many flat faces does a cylinder have?
The three key steps
- 1For a flat shape, count the sides and corners.
- 2For a solid shape, count the flat faces.
- 3Turn it over to find more.
Mistakes to listen for
- Counting one side twice, or losing track of where they started, and saying a square has 5 sides.
- Thinking a rectangle and a square have nothing in common, not noticing both have 4 sides and 4 corners.
- Describing shapes only by color or size, saying "the red one is bigger" instead of naming sides or corners.
The lesson shows every step, so your child sees why it works. Read our parent's guide to comparing shapes by their sides and corners →
Is your child ready to practice what they've learned?
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More Kindergarten 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 comparing shapes by their sides and corners, 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 comparing shapes by their sides and corners 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 comparing shapes by their sides and corners
Questions at your child's level, about five minutes a day, on comparing shapes by their sides and corners and whatever PK-5 skills they need to develop. Unlimited practice, free forever.
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