Grams, kilograms and liters
Holding a kilogram in their hands gives your child a feel for weight that no chart can, and that feel helps them judge whether an answer is believable, such as noticing that a pencil cannot weigh 5 kilograms. In 4th grade they convert between units, like 2 kilograms to 2,000 grams, and later science classes measure in metric units throughout. It is practical at home as well, from reading food labels to filling a 2-liter bottle.
In this video, your child will learn to measure and estimate grams, kilograms and liters.
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
About how heavy is a big book?
Example 2
A pumpkin weighs 4 kg. A bag of potatoes weighs 3 kg. How many kilograms do they weigh together?
Your child's turn
A jug has 13 liters. We pour out 5. How many liters are left?
The three key steps
- 1Gram: paper clip. kg: big book.
- 2Liters: how much liquid
- 3On, in: add. Off, out: subtract.
Mistakes to listen for
- Picking the wrong unit for an estimate, such as saying an apple weighs about 200 kilograms.
- Assuming a bigger object is always heavier, so a large pillow must outweigh a small rock.
- Reading a scale or container at the wrong line, such as viewing the liquid at an angle or skipping what each mark stands for.
The lesson shows every step, so your child sees why it works. Read our parent's guide to weighing things and measuring liquids →
Is your child ready to practice what they've learned?
Bobby's Math Club offers unlimited practice for free.
Join the clubMore kid-friendly lessons
More 3rd grade Measurement & Data, 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 weighing things and measuring liquids, 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 weighing things and measuring liquids 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 weighing things and measuring liquids
Questions at your child's level, about five minutes a day, on weighing things and measuring liquids and whatever PK-5 skills they need to develop. Unlimited practice, free forever.
Join the club