Welcome to the World of Capacity!
Hi there, Maths explorers! Have you ever wondered how much juice is in your juice box, or how much water your bottle can hold? Today, we're going to learn all about capacity. It sounds like a big word, but it's super simple and you use it every day!
By the end of these notes, you'll be a capacity champion, able to measure liquids and understand how much containers can hold. This is really useful for cooking, science experiments, or just knowing who has more milkshake!
Section 1: What is Capacity?
So, what does Capacity mean?
Capacity is the total amount of liquid that a container can hold.
Think of it like a container's tummy! A big bottle has a big tummy, so it has a large capacity. A small cup has a small tummy, so it has a small capacity.
Comparing Capacity (The Fun Way!)
Before we even use numbers, we can compare the capacity of different containers.
1. Just by Looking (Intuitive Comparing)
Imagine you have a big jug and a small glass. Just by looking, you can probably guess that the jug can hold more water. Your eyes help you make a smart guess!
2. By Pouring (Direct Comparing)
If you have two bottles that look similar, how can you be sure which one holds more? You can fill one bottle with water and then pour it into the other. If the water overflows, the first bottle had a bigger capacity! If there's still room, the second bottle has a bigger capacity.
3. Using a Smaller Container (Comparing with Improvised Units)
Imagine you need to fill a big bucket, but you only have a little teacup. You can measure the bucket's capacity by counting how many teacups of water it takes to fill it up! If it takes 20 teacups for the red bucket and 30 teacups for the blue bucket, you know the blue bucket has a larger capacity.
Key Takeaway for Section 1
Capacity is how much a container can hold. We can compare capacities by looking, by pouring from one container to another, or by counting how many times a small container fills a bigger one.
Section 2: The Magic Units - Litres (L) and Millilitres (mL)!
To measure capacity properly, we use special units. Let's meet the two most important ones!
Meet the Millilitre (mL)
A millilitre is a very small amount of liquid. We use it to measure small capacities.
The short way to write millilitre is mL.
A medicine spoon holds about 5 mL.
A few drops of rain might be 1 mL.
Meet the Litre (L)
A litre is a much bigger unit. It's made up of many, many millilitres! We use it to measure larger capacities.
The short way to write litre is L. (Sometimes you might see a lowercase 'l' too).
A large carton of milk or juice is often 1 L.
A big water bottle might hold 1 L.
The Super Important Rule!
This is the most important thing to remember in this whole chapter. Are you ready?
One litre is the same as one thousand millilitres.
$$1 \text{ L} = 1000 \text{ mL}$$
Memory Aid!
Imagine a big 1 Litre jug. To fill it up, you would need to pour in 1000 tiny millilitres. "Milli" sounds a bit like "million," but in measurement, it means "thousandth"!
Did you know?
A little cube that is 1 cm on each side can hold exactly 1 mL of water!
Key Takeaway for Section 2
We measure small capacities in millilitres (mL) and larger ones in litres (L). The golden rule is: 1 L = 1000 mL.
Section 3: Measuring and Reading Capacity
We use tools like measuring cups and measuring jugs to find the exact capacity.
How to Use a Measuring Cup
A measuring cup has lines on the side called a scale. These lines have numbers next to them to tell you how much liquid is inside.
How to Read it: Step-by-Step
1. Place the cup on a flat, even surface. Don't hold it in your hand!
2. Carefully pour the liquid in.
3. Get down so your eyes are level with the liquid. Don't look from above or below.
4. Read the number on the scale that the top of the liquid touches. That's your measurement! Always check if the unit is mL or L.
Common Mistake to Avoid!
If you look down from the top, the measurement might look lower than it is. If you look up from below, it might look higher. Always look straight on to be accurate!
Key Takeaway for Section 3
To measure capacity, use a measuring cup on a flat surface. Read the scale with your eyes level with the liquid to get an accurate measurement.
Section 4: Awesome Conversions!
This is where we become Maths wizards and change units from L to mL and back again. Don't worry, it's just about using our magic number: 1000.
Changing Litres (L) to Millilitres (mL)
When we go from a BIG unit (L) to a SMALL unit (mL), we get a much bigger number. So we multiply!
Rule: Multiply the number of litres by 1000.
Example 1: Change 4 L into mL.
Since 1 L = 1000 mL, we do:
$$4 \times 1000 = 4000$$
So, 4 L = 4000 mL.
Example 2: Change 2 L 500 mL into mL.
This is a mix! Let's break it down.
1. First, convert the litres: 2 L = 2000 mL.
2. Now, add the extra millilitres: 2000 mL + 500 mL = 2500 mL.
So, 2 L 500 mL = 2500 mL. You did it!
Changing Millilitres (mL) to Litres (L) and Millilitres (mL)
When we go from a SMALL unit (mL) to a BIG unit (L), we are making groups of 1000.
Rule: The digit in the thousands place tells you the litres. The rest is the millilitres.
Example 1: Change 7000 mL into L.
The number 7 is in the thousands place.
So, 7000 mL = 7 L.
Example 2: Change 1250 mL into L and mL.
Let's look at the number 1250.
1. The digit in the thousands place is 1. This is our number of litres. So, 1 L.
2. The rest of the number is 250. This is our leftover millilitres. So, 250 mL.
Put them together: 1250 mL = 1 L 250 mL.
Quick Review Box
L to mL: Multiply by 1000. (e.g., 5 L = 5000 mL)
mL to L: The thousands digit is the litres. (e.g., 3400 mL = 3 L 400 mL)
Key Takeaway for Section 4
Converting is easy when you remember 1 L = 1000 mL. To go from L to mL, multiply by 1000. To go from mL to L, look for groups of 1000.
Section 5: Comparing Capacities
Which is more, 2 L or 2500 mL? To answer questions like this, we need to make the units the same first!
Step-by-Step Guide to Comparing
Let's compare 1 L 500 mL and 1200 mL.
Step 1: Make the units the same.
It's usually easiest to change everything to the smaller unit, millilitres (mL).
Let's convert 1 L 500 mL to just mL.
1 L = 1000 mL.
1000 mL + 500 mL = 1500 mL.
Step 2: Compare the numbers.
Now we are comparing 1500 mL and 1200 mL.
We know that 1500 is bigger than 1200.
Step 3: Write your answer.
So, 1 L 500 mL is greater than 1200 mL.
Key Takeaway for Section 5
To compare capacities, you must first convert them to the same unit (like mL). Then you can see which number is bigger or smaller.
Great job! You've learned all the basics of capacity. Keep practising, and soon you'll be a measurement master!