Find volume by counting cubes
Counting cubes shows your child what a volume number really means, so the formula that comes next is not a string of letters to memorize. Working with cubic inches, cubic centimeters, and cubic feet also teaches that the size of the unit changes the count. That understanding supports surface area and volume work in 6th grade and measuring in science classes.
In this video, your child will learn to find volume by counting cubes.
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
The bottom layer has 4 cubes. The box is 2 layers tall. Volume = ? cubic units
Example 2
A box is 4 cm long, 2 cm wide and 3 cm tall. Volume = ? cubic centimeters
Your child's turn
A box is 3 in long, 3 in wide and 3 in tall. Volume = ? cubic inches
The three key steps
- 1Count the bottom layer.
- 2Add it for every layer.
- 3The total is the volume.
Mistakes to listen for
- Counting only the cubes they can see, so a 3 by 4 by 2 stack is counted as 20 or fewer, not 24.
- Writing square inches instead of cubic inches, mixing up the unit for flat surfaces with the unit for solid space.
- Counting each outside face separately and adding, so corner and edge cubes get counted two or three times.
The lesson shows every step, so your child sees why it works. Read our parent's guide to finding volume by counting cubes →
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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 finding volume by counting cubes, 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 finding volume by counting cubes 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 finding volume by counting cubes
Questions at your child's level, about five minutes a day, on finding volume by counting cubes and whatever PK-5 skills they need to develop. Unlimited practice, free forever.
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