Chapter 8: Weigh it, Pour it

At the kirana shop, the shopkeeper asks: "Half kilo or one kilo?" At home, mother says: "Get me 1 litre of milk." Today, let's master weight and capacity.

What we'll learn

• Weight: grams (g) and kilograms (kg).
• Capacity: millilitres (ml) and litres (l).
• Convert between units.
• Use weighing scales and measuring jugs.

The big idea

Weight is how heavy a thing is. We measure small weights (like a packet of biscuits) in grams, and bigger weights (like rice bags) in kilograms.

1 kg = 1000 g.

Capacity is how much liquid a container can hold. A small bottle holds millilitres; a big bucket holds litres.

1 litre = 1000 ml.

A weighing scale has a needle that points to the weight. The two-pan balance is even simpler , put the object on one side, known weights on the other. When the two sides balance, you've found the weight.

For capacity, we use measuring jugs. They have marks at every 100 ml or 250 ml.

Choosing units matters. A pinch of salt is in grams, not kilograms. A glass of water is in millilitres, not litres.

Explore with examples

1. Convert 3 kg to grams.

1 kg = 1000 g. So 3 kg = 3 × 1000 = 3000 g.

2. Convert 2500 ml to litres.

2500 ÷ 1000 = 2 l 500 ml (or 2.5 l).

3. Aman buys 250 g of dal and 750 g of rice. Total weight?

250 + 750 = 1000 g = 1 kg.

4. A tank holds 50 litres of water. Each bucket holds 5 litres. How many buckets to fill the tank?

50 ÷ 5 = 10 buckets.

Hands-on activities

Kitchen Weigher

Use a small kitchen scale. Weigh 5 things , a banana, a notebook, a slipper, a spoon, a small toy. Order them from lightest to heaviest.

Tumbler Test

Take a 1-litre bottle. How many full tumblers fill it? Now do the same with a coffee mug. Note the difference.

Balance Game

Use a hanger and 2 paper cups to make a balance. Put coins in one cup. Add small stones to the other until they balance. You've matched their weights without numbers!

Try it yourself

1. Convert 4 kg to grams.
2. Convert 1500 ml to litres.
3. A bag of sugar weighs 5 kg. The shopkeeper pours half. How much in grams is poured?
4. A jug holds 2 l. Each glass holds 250 ml. How many glasses?
5. Order: 1 kg, 500 g, 1500 g, 750 g , lightest to heaviest.
6. Add: 2 l 300 ml + 1 l 800 ml.
7. Which unit best for a watermelon: g or kg?

Recap

• Weight in g and kg. 1 kg = 1000 g.
• Capacity in ml and l. 1 l = 1000 ml.
• Pick the unit that fits the size of the thing.
• Weighing scales and measuring jugs are our friends.