Jugs and Mugs: Understanding Capacity (Class 2 Maths)

What is Capacity? Thinking About How Much Things Hold

Capacity is the amount of liquid that a container can hold. Think of it as the total space inside. A big bucket has a lot of space inside, so it has a large capacity. A small teacup has very little space inside, so it has a small capacity.

How do we measure capacity? In this chapter, we don't use fixed units like litres yet. Instead, we use other containers to measure! For example, we can say, "This jug has a capacity of 10 glasses of water." Here, the 'glass' is our unit of measurement. If another jug holds only 5 of the same glasses, we know the first jug has a larger capacity.

Imagine you have a big water bottle and a small juice box. Which one can hold more liquid? The water bottle, of course! This is because its capacity is greater than the juice box's capacity. We can check this by filling the juice box with water and pouring it into the empty water bottle. You will see there is still a lot of empty space left in the bottle. This simple experiment shows that the bottle has a larger capacity.

Worked Examples: Comparing and Measuring

• Problem: A bucket can be filled with 5 jugs of water. A tub can be filled with 10 jugs of water. Which has more capacity? Solution: Step 1: Note the number of jugs needed to fill the bucket. It is 5 jugs. Step 2: Note the number of jugs needed to fill the tub. It is 10 jugs. Step 3: Compare the two numbers, 5 and 10. We know that 10 is bigger than 5. Final answer: The tub has more capacity because it holds more jugs of water.
• Problem: Seema used 3 glasses of water to fill her bottle. Her friend Aman used 5 glasses of water to fill his bottle. Who has the smaller bottle? Solution: Step 1: Seema's bottle holds 3 glasses. Step 2: Aman's bottle holds 5 glasses. Step 3: Compare the numbers 3 and 5. The number 3 is smaller than 5. Final answer: Seema has the smaller bottle because it holds fewer glasses of water.
• Problem: A kettle holds 8 cups of tea. A thermos holds 15 cups of tea. How many more cups does the thermos hold? Solution: Step 1: The thermos holds 15 cups. Step 2: The kettle holds 8 cups. Step 3: To find 'how many more', we subtract the smaller number from the bigger number. So, we calculate 15 - 8. Step 4: 15 - 8 = 7. Final answer: The thermos holds 7 more cups of tea than the kettle.

Important Points to Remember

• Don't judge by height alone! A short, wide bowl can sometimes hold more water than a tall, thin glass. Always think about the total space inside.
• Use the same measuring cup! When you compare two pots, make sure you fill them using the same mug or glass. If you use a small mug for one and a big mug for the other, your comparison will be wrong.
• Capacity is about how much a container can hold when it's full, not how much it has in it right now. An empty bucket still has a large capacity!

Practice Questions with Solutions

• Q: A small pot holds 15 cups of water. A big pot holds 25 cups of water. How many more cups of water does the big pot hold? A: Step 1: Identify the capacity of the big pot, which is 25 cups. Step 2: Identify the capacity of the small pot, which is 15 cups. Step 3: To find out 'how many more', we need to subtract the smaller number from the bigger number. So, we calculate 25 - 15. Step 4: 25 - 15 = 10. Final answer: The big pot holds 10 more cups of water.
• Q: A doctor told Priya to drink 8 glasses of water every day. If her water bottle holds 4 glasses, how many times does she need to fill her bottle completely to drink 8 glasses? A: Step 1: Total water needed is 8 glasses. Step 2: The bottle's capacity is 4 glasses. Step 3: We need to see how many '4s' make '8'. We can add: 4 (first bottle) + 4 (second bottle) = 8. Step 4: Counting the number of times she filled the bottle, we see it is 2 times. Final answer: Priya needs to fill her bottle 2 times.
• Q: A jug can be filled with 2 bottles. A bucket can be filled with 5 jugs. How many bottles are needed to fill the bucket? A: Step 1: We know 1 jug = 2 bottles. Step 2: A bucket needs 5 jugs to be filled. Step 3: We need to find the total number of bottles for 5 jugs. So, we add the bottles for each jug: 2 + 2 + 2 + 2 + 2. Step 4: 2 + 2 + 2 + 2 + 2 = 10. Final answer: 10 bottles are needed to fill the bucket.
• Q: Three friends have bottles of capacity 5 cups, 7 cups, and 6 cups. What is the total capacity of all three bottles together? A: Step 1: Write down the capacity of each bottle: 5 cups, 7 cups, and 6 cups. Step 2: To find the total capacity, we need to add them all together. Step 3: Calculate 5 + 7 + 6. Step 4: 5 + 7 = 12. Then, 12 + 6 = 18. Final answer: The total capacity of all three bottles is 18 cups.

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