Grade 3 (age 8-9)

Capacity and Weight

Capacity is how much water or liquid a container can hold, while weight is how heavy an object is. We measure the capacity of a milk carton or a bottle in liters and milliliters, and the weight of an apple or a watermelon in grams and kilograms. Since 1 liter is 1000 milliliters and 1 kilogram is 1000 grams, you can switch between the big unit and the small unit. On this page you can fill a beaker and place objects on a scale, changing the units to estimate and compare capacity and weight.

What is Capacity?

🥛 Amount a Container Can Hold

①A milk carton holds 1000 mL (1 L)

②A paper cup is about 200 mL

③Capacity measures liquid volume

Capacity Conversion

Milliliters (mL)1200 mL

💡 1 L = 1000 mL

①1 liter is 1000 milliliters

②1500 mL = 1 L 500 mL

③Convert between L (big) and mL (small)

Weight Conversion

Grams (g)2500 g

⚖️ 1 kg = 1000 g

①1 kilogram is 1000 grams

②2500 g = 2 kg 500 g

③Heavy → kg, light → g

Summary

Capacity Units

1 L = 1000 mL

Liter to milliliter — 1000× relationship

Weight Units

1 kg = 1000 g

Kilogram to gram — 1000× relationship

Conversion Method

Big → small: ×1000

Small → big: ÷1000

🎯 Key Points

①Capacity: amount a container holds (L, mL)

②Weight: heaviness of an object (kg, g)

③1 L = 1000 mL, 1 kg = 1000 g

④Big ↔ small: ×1000, ÷1000

⑤Pick the right unit for real life

Examples and Unit Test

Example 1

How many mL is 2 L?

1 L = 1000 mL.

2 L = 2 × 1000 = 2000 mL.

▸ 2000 mL

To convert a big unit (L) to a small unit (mL), multiply by 1000.

Example 2

How many kg and g is 2500 g?

Since 1 kg = 1000 g, see how many 1000s fit in 2500 g.

2500 = 2000 + 500, so it is 2 kg 500 g.

▸ 2 kg 500 g

Group every 1000 g into 1 kg and write it as kg and g.

Unit Test

How many g is 1 kg?

①10 g

②100 g

③1000 g

④500 g

▸ ③ 1000 g

The weight-unit relationship is 1 kg = 1000 g.

So 1 kg = 1000 g.

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