Capacity Measurements
Primary 4 · Mathematics
Capacity Measurements
Lesson 4 of 4
20 min
Let's begin
Habimana's class is planning a sports day. The teacher sends Habimana to the shop to look at drinks.
Some bottles say 1.5 L. Some say 800 mL. A big jug says 2 L, and a carton says 1 250 mL. "Which one holds the most?" Habimana wonders.
Today you will compare capacities and solve real problems with them.
To compare capacities, first change them all to the same unit. Millilitres are often easiest, because then there are no decimals.
Worked example 1
Order 1.5 L, 800 mL, 2 L and 1 250 mL from smallest to largest.
Step 1 Change to mL: 1.5 L = 1 500 mL and 2 L = 2 000 mL.
Step 2 Compare 1 500, 800, 2 000 and 1 250.
Step 3 Order: 800 mL, 1 250 mL, 1.5 L, 2 L.
Careful! 800 mL is less than 1.5 L, even though 800 is a bigger number than 1.5. The units are different, so you cannot compare the numbers alone.
Worked example 2
How many times as much does a 20 L jerrycan hold as a 500 mL bottle?
Step 1 Same unit: 20 L = 20 000 mL.
Step 2 Divide: 20 000 ÷ 500 = 40.
The jerrycan holds 40 times as much. You could fill 40 small bottles from one jerrycan.
Worked example 3
A school water tank holds 2 000 L. The school uses 250 L each day. How many days will a full tank last?
2 000 ÷ 250 = 8. A full tank lasts 8 days.
Worked example 4
At the milk kiosk, 1 L of milk costs 600 Frw. Gatete buys 3 L 500 mL. How much does he pay?
Step 1 3 L cost 3 × 600 = 1 800 Frw.
Step 2 500 mL is half a litre, so it costs half of 600 Frw, which is 300 Frw.
Step 3 1 800 + 300 = 2 100 Frw.
Worked example 5
Mama has a full 20 L jerrycan. She fills 6 bottles of 1.5 L each. How much water is left?
Step 1 1.5 L = 1 500 mL, and 6 × 1 500 = 9 000 mL = 9 L.
Step 2 20 − 9 = 11 L left.
Tip
Units before numbers. Before you compare, change every amount into the same unit. A big number in mL can still be a small amount!
Work each one in your exercise book first. Then tap Show answer to check.
Which is more: 2.5 L or 2 300 mL?
Answer: 2.5 L. It is 2 500 mL, and 2 500 is more than 2 300.
Order from smallest to largest: 3 L, 2 900 mL, 3.25 L.
Answer: 2 900 mL, 3 L, 3.25 L. In mL they are 2 900, 3 000 and 3 250.
How many 250 mL glasses can you fill from 3 L of juice?
Answer: 12 glasses. 3 L = 3 000 mL, and 3 000 ÷ 250 = 12.
A tank can hold 1 500 L. It has 875 L in it now. How many more litres will fill it?
Answer: 625 L, because 1 500 − 875 = 625.
Milk costs 600 Frw for 1 L. How much do 5 L cost? How much does half a litre cost?
Answer: 5 L cost 5 × 600 = 3 000 Frw. Half a litre costs 600 ÷ 2 = 300 Frw.
What you learned today
Sources and credits
The stories, Rwandan examples, drawings and practice questions were written by Ganzaa.
Quick check
Which one holds the most?
