Weight — Grade 2 Mathematics
Weight tells us how heavy something is. We use weight every day — weighing ingredients for cooking, checking luggage at the airport, or finding out how much a parcel weighs before posting it. In Grade 2, we learn the two standard units of weight and how to convert between them.
Grams and Kilograms
Kilogram (kg) — used for heavier objects (a bag of sugar = 1 kg; a child ≈ 30 kg).
1 kg = 1000 g
Conversion rules:
kg → g: multiply by 1000
g → kg: divide by 1000
| Object | Approximate Weight |
|---|---|
| A grain of rice | 0.03 g |
| A pen | 10 g |
| A book | 400 g |
| A bag of flour | 1 kg (1000 g) |
| A watermelon 🍉 | 4–5 kg |
Worked Examples
A melon 🍈 is placed on a scale. The pointer rests between the 1000 g and 1500 g marks, at the exact middle. How heavy is the melon?
Convert 4 kg 300 g to grams only.
- 4 kg = 4 × 1000 = 4000 g
- Add the remaining: 4000 + 300 = 4300 g
You buy a bag of flour weighing 1.5 kg and a bag of sugar weighing 750 g. What is the total weight in grams and kilograms?
- Convert 1.5 kg = 1500 g
- Total = 1500 + 750 = 2250 g
- In kg: 2250 ÷ 1000 = 2.25 kg = 2 kg 250 g
Practice Questions
Try these! Work out the answers first, then check.
1. Convert 3 kg to grams.
2. Convert 2500 g to kg.
3. A parcel weighs 3 kg 400 g. Convert to grams only.
4. Which is heavier: 1.8 kg or 1650 g?
5. A cake needs 850 g of flour. You have 1.5 kg. How much flour is left after baking?
Key Points to Remember
- Weight tells us how heavy an object is.
- 1 kg = 1000 g. kg → g: × 1000. g → kg: ÷ 1000.
- Use grams for light objects; kilograms for heavier ones.
- Always convert to the same unit before comparing or adding weights.
- Check scale markings — each division may represent 50 g, 100 g, 200 g, etc.