MathGrade 3ages 8–9
🍬 Kilogram
A child who says a big balloon must weigh more than a small stone is judging weight by size, because that's usually a decent guess — until an object filled with air breaks the pattern.
Try this lesson freeNo card needed. The first lesson is free.
Download on the App StoreWhat your child learns
- 1 kilogram = 1000 grams.
- A bag of sugar at home is about a kilo.
- A feather is light — grams, not a kilo.
- A big balloon can be lighter than a small stone. Volume is not the same as weight.
The mistake most kids make here
Whatever takes more space is always heavier.
Try one question
1 kg = how many grams?
1 kg
- 100
- 1000
- 10
Answer
1000 — Yes! One kilogram = exactly a thousand grams.
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 kg = 1000 g. A feather is measured in grams.
How to help at home
Size and weight often do go together in everyday life, so a child hasn't done anything wrong by guessing that way — they just haven't yet met enough exceptions to know the rule breaks down.
Find a kitchen scale and compare a large, light object (a balloon, a bag of chips, a pillow) against a small, dense one (a stone, a spoon, a small toy car). Let your child hold each pair first and guess, then weigh them to check.
When the "bigger is heavier" guess is wrong, ask: "what's this made of — is it packed full, or mostly air?" That question moves the conversation from size to density, which is the actual thing that predicts weight.
A sign they've got it: shown a large empty box next to a small full jar of coins, they correctly guess the jar is heavier before you put either one on a scale.
Questions parents ask
- Why does my child think bigger things always weigh more?
- It's a reasonable pattern most of the time — a bigger apple usually does weigh more than a small one. The rule only breaks with objects that are mostly air or hollow, like balloons or empty boxes, and that's exactly where practice helps.
- How many grams are in a kilogram?
- 1,000 grams make one kilogram. A bag of sugar or flour at home is a good everyday reference for about one kilogram.
- What household items are good for weight comparisons?
- A balloon versus a stone, a pillow versus a shoe, or a bag of cotton balls versus a bag of coins all make the size-versus-weight point clearly, especially on a kitchen scale.
- How does Maya teach kilograms and grams?
- Maya has the child predict which of two objects is heavier before checking on a scale, so surprising results — like a big balloon weighing less than a small stone — get noticed and explained, not just corrected.
No card needed. The first lesson is free.
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