Join shapes to make bigger shapes
Every time your child fits two triangles into a rectangle, they are building spatial reasoning: the ability to picture shapes and move them in their mind. It also shows that one shape can be made of others, which leads to splitting shapes into halves and fourths in 1st grade, to fractions in 3rd grade, and to finding area by breaking a shape into parts. The same skill helps with puzzles, building toys, and reading maps.
In this video, your child will learn to join shapes to make bigger 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
What shape do the two triangles make?
Example 2
What shape do the two squares make?
Your child's turn
What shape do they make?
The three key steps
- 1Join them with full sides touching.
- 2Count the sides, and look at how long they are.
- 3Then say its name.
Mistakes to listen for
- Joining two triangles corner to corner instead of side to side, leaving a gap instead of a rectangle.
- Letting sides touch only partly, so edges overlap or leave a step and the new shape comes out wrong.
- Trying one position, deciding the pieces do not fit, and giving up without turning or flipping them.
The lesson shows every step, so your child sees why it works. Read our parent's guide to putting shapes together to make new shapes →
Is your child ready to practice what they've learned?
Bobby's Math Club offers unlimited practice for free.
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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 putting shapes together to make new 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 putting shapes together to make new 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 putting shapes together to make new shapes
Questions at your child's level, about five minutes a day, on putting shapes together to make new shapes and whatever PK-5 skills they need to develop. Unlimited practice, free forever.
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