MathGrade 3ages 8–9
💧 Litre
A child who says 500 mL is more than a litre is comparing the numbers 500 and 1 directly, without yet connecting millilitres to litres as the same kind of amount measured in smaller units.
Try this lesson freeNo card needed. The first lesson is free.
Download on the App StoreWhat your child learns
- 1 litre = 1000 millilitres.
- An ordinary water bottle is about a litre.
- 500 mL = half a litre.
- A big number of mL can still be less than one litre.
The mistake most kids make here
500 mL looks like more than a litre because 500 is a big number.
Try one question
1 L = how many mL?
1 L
- 100
- 1000
- 10
Answer
1000 — Yes! A thousand mL = one litre.
How Maya teaches it
Your child tells Maya what they did in class. She teaches this topic at her desk, asks questions with tappable answers, and when the answer is wrong she explains why that answer was tempting instead of saying “try again”. She remembers what did not land and comes back to it.
Your child has it when they can: 1 L = 1000 mL, and 500 mL is half a litre.
How to help at home
This mistake mirrors a common one with money or grams: a bigger-looking number in a smaller unit can seem like more, when it isn't, once you know how the units relate.
Fill a one-litre bottle with water, then pour it into a measuring cup marked in millilitres, or into two smaller 500 mL bottles side by side. Watching the same litre of water fill two 500 mL containers exactly makes the relationship visible rather than abstract.
When "500 mL is more than a litre" comes up, ask: "if I poured your 500 mL into this litre bottle, would it fill it all the way, or only halfway?" Actually pouring it and watching it stop halfway is more convincing than any explanation.
A sign they've got it: they can say, without measuring, that 1,200 mL is more than a litre, because it's more than the 1,000 mL a litre actually holds.
Questions parents ask
- Why does my child think 500 mL is more than a litre?
- The number 500 looks large compared to the number 1, especially if the units "mL" and "L" haven't yet been connected as different-sized measurements of the same thing. Pouring liquid between marked containers makes the relationship concrete.
- How many millilitres are in a litre?
- 1,000 millilitres make one litre. An ordinary water bottle is a good everyday reference for about one litre.
- What household items help teach litres and millilitres?
- A one-litre water bottle, a kitchen measuring cup marked in millilitres, and any two half-litre bottles work well for pouring comparisons.
- How does Maya teach litres and millilitres?
- Maya has the child compare and pour real quantities before comparing the numbers on paper, so "500 mL" gets tied to an actual amount rather than judged purely by which digit looks bigger.
No card needed. The first lesson is free.
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