Capacity (I): Litre

1Summary 重點摘要

1 L = 1000 mL. Kettle uses L.

2Vocabulary cards Vocabulary

3Step by step Steps

1. Part 1: Capacity means how much it holdsCapacity is how much liquid a container can hold. A cup holds 250 mL of water, and a kettle holds 1.7 L. Capacity talks about the liquid inside, not how heavy the container itself is, so do not mix the two up: a large thin plastic basin may hold more than a small thick glass bottle. A common mistake is to think a bigger container always holds more; the shape and depth matter too. Also separate 'how much can be held' from 'how much is held now'; an empty bottle still has its capacity. Capacity is a container's ability, not its present state.
2. Part 2: Big drinks use LContainers that hold a lot use litres (L). A large bottle of soft drink is 1.5 L, a kettle is 2 L, a bucket holds about 10 L, and a rice cooker about 2 to 3 L. Their labels all show L, because writing such numbers in mL would be very big; 2 L written as 2000 mL is clumsy. A common mistake is to mix up the symbols: L is the litre and mL the millilitre, and mL is a thousand times smaller than L. Shoppers who misread the unit may think 500 mL is more than 1.5 L; in fact 500 mL is half a litre, and 1.5 L is three times that.
3. Part 3: Small drinks use mLSmall amounts use millilitres (mL). A carton of milk is 250 mL, a bottle of eye drops is 10 mL, a spoonful is about 15 mL, and a tube of glue about 40 mL. Using mL for small amounts makes them clear at a glance, and doses of medicine must be exact: if the doctor writes 5 mL, not a drop more or less will do. A common mistake is to think eye drops and milk cartons hold similar amounts; 10 mL is only one twenty-fifth of 250 mL, a far bigger gap than imagined. Keep handy references in mind: a spoonful is about 15 mL and a drink carton about 250 mL, which gives a basis for estimating small capacities.
4. Part 4: 1 L = 1000 mLLitres and millilitres are linked by 1 L = 1000 mL. Pour a whole 1 L bottle into small 250 mL cups: 1000 ÷ 250 = 4, so it fills exactly 4 cups. The other way, 4 cups of 250 mL together make 1000 mL, which is 1 L. A common mistake is to remember the link as 1 L = 100 mL, confused with the hundreds of length units, which ruins every conversion. One way to remember: 1 m = 100 cm uses a hundred, but 1 L = 1000 mL uses a thousand. Doing the pouring experiment once with your own hands fixes the relation especially firmly.
5. Part 5: How to convertConverting follows fixed rules. Bigger unit to smaller unit, multiply by 1000: 3 L = 3 × 1000 = 3000 mL. Smaller to bigger, divide by 1000: 4000 mL = 4000 ÷ 1000 = 4 L. Do not turn the direction around: litres to millilitres should make the number bigger, millilitres to litres smaller. A common mistake is to convert 2.5 L into 25 mL, multiplying by only 10; the correct answer is 2.5 × 1000 = 2500 mL. After converting, check the direction of change; if the number shrank when it should have grown, the multiplication and division were swapped, and correcting at once blocks most conversion errors.
6. Part 6: Word problemsWord problems need matching units first. Soup needs 1 L 500 mL of water: change it to 1000 + 500 = 1500 mL. Using a 500 mL measuring cup: 1500 ÷ 500 = 3, so 3 cups are enough. If the question asks 'how much more is needed', subtract; if it asks 'is it enough', compare the sizes. A common mistake is to subtract numbers with different units directly, working out 2 L − 750 mL as 2 − 750 and getting a negative; first convert to one unit, 2000 − 750 = 1250 mL, then decide from the question whether to answer in mL or as 1 L 250 mL.

4Diagrams Diagrams

5Worked example Example

6Common mistakes Mistakes

7Quick check Quick check

8Recap Recap

• Capacity = how much liquid a container holds
• 1 L = 1000 mL
• Big amounts use L (kettles, large bottles); small use mL (milk cartons, medicine)
• L to mL × 1000; mL to L ÷ 1000
• Match units before adding or subtracting