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Step 5: Multiplication and first fractions

Time, mass, and liquid volume

Step 5 · Multiplication and first fractions topics

Tell time to the nearest minute, work out how long something takes, and measure mass in grams and kilograms and liquid volume in liters.

Time to the minute

The minute hand goes all the way round in 60 minutes. Each number on the clock is 5 minutes on, and each small mark between the numbers is 1 minute. Count by 5s to the last number the minute hand passed, then count on the small marks.

The minute hand is 2 marks past the 9: 45 + 2 = 47 minutes. The time is 3:47.

The hour hand is between the 3 and the 4, so the hour is still 3. The time is 3:47, which is 13 minutes to 4.

How long it takes

Elapsed time is how much time passes between a start and an end. Count on from the start: first to the next hour, then whole hours, then the minutes that are left.

Example: Elapsed time

A film starts at 2:35 and ends at 4:10. How long is it?

  1. From 2:35 to 3:00 is 25 minutes.
  2. From 3:00 to 4:00 is 1 hour.
  3. From 4:00 to 4:10 is 10 minutes.
  4. 25 + 10 = 35 minutes, plus the hour.

Answer1 hour 35 minutes

The film starts at 2:35 and ends at 4:10: 1 hour 35 minutes later.

Grams, kilograms and liters

Mass is how heavy something is. A paper clip is about 1 gram (g). A liter bottle of water is about 1 kilogram (kg), and 1 kilogram is 1,000 grams.

1 kilogram balances two 500 gram weights: 1 kg = 1,000 g.

Liquid volume is how much liquid a container holds. A large water bottle holds about 1 liter (L); a bathtub holds about 150 liters.

Example: Adding masses

A bag of apples has a mass of 3 kg and a bag of potatoes 5 kg. What is their total mass?

  1. Both are in kilograms.
  2. 3 + 5 = 8.

Answer8 kilograms

Example: Sharing liquid

24 liters of water is shared equally into 4 buckets. How much goes in each bucket?

  1. Share 24 into 4 equal parts.
  2. 24 ÷ 4 = 6.

Answer6 liters

Try it yourself

Work each one on paper first, then open the answer to check.

  1. The hour hand is just past the 8, and the minute hand points 3 marks after the 4. What time is it?

    Show answer

    8:23.

  2. Recess starts at 10:45 and lasts 20 minutes. When does it end?

    Show answer

    11:05.

  3. Which is the better unit for the mass of a dog: grams or kilograms?

    Show answer

    Kilograms.

  4. A jug holds 2 liters. How much do 5 jugs hold?

    Show answer

    10 liters.

  5. One box has a mass of 900 g and another has 350 g. How much heavier is the first?

    Show answer

    550 grams.

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