RemeliaMaths Year 3 Measurement
Year 3 measurement: six questions and the common mistakes
Under each answer are the wrong answers a child often gives to it, four different mistakes on this page, and what Remelia tells the child who gives one.
Questions written by Remelia for the objectives of the national curriculum for England; not taken from any test paper.
Six questions
-
Which is longer: 7 m or 70 cm?
- A They are the same length
- B 7 m
- C 70 cm
Show the answer to question 1
Answer: B · 7 m
Why:
Put both in the same unit. 7 m is 700 cm, which is longer than 70 cm.
Common mistakes:
- C · 70 cm: It looks as if you compared the numbers without their units. A bigger number can be a smaller amount when its unit is smaller: write both in the same unit first, then compare.
-
A rectangle is 13 cm long and 12 cm wide.
What is its perimeter?
- A 150 cm
- B 500 cm
- C 50 cm
- D 60 cm
Show the answer to question 2
Answer: C · 50 cm
Why:
Perimeter is all the way round: 13 + 12 + 13 + 12 = 50 cm. Or 2 × (13 + 12).
Common mistakes:
- 156: That is the area: the length multiplied by the width. The perimeter is the distance all the way round, so add up every side.
-
A night train leaves at 00:25.
What time is that on a 12-hour clock?
- A 12:25 pm
- B 2:25 am
- C 12:25 am
- D 2:25 pm
Show the answer to question 3
Answer: C · 12:25 am
Why:
00:25 is 25 minutes after midnight, the start of the day, so it is am. The hour 00 is written 12. So it is 12:25 am.
Common mistakes:
- A · 12:25 pm: It looks as if you swapped am and pm at 12. Midnight starts the day, so 00:30 is 12:30 am; midday starts the afternoon, so 12:30 is 12:30 pm.
-
It is 11:50.
What time will it be in 30 minutes? Write it like 09:35.
Show the answer to question 4
Answer: 12:20 (also accept 12.20, 1220, 12:20 pm)
Why:
11:50 + 30 minutes: go up to the next hour first if you need to. → 12:20.
Common mistakes:
- 11:80: It looks as if you counted the minutes past 60. An hour has 60 minutes, so at 60 the hour goes up by one and the minutes start again from 00.
-
Which is longer: 300 cm or 3 m?
- A They are the same length
- B 3 m
- C 300 cm
Show the answer to question 5
Answer: A · They are the same length
Why:
Put both in the same unit. 3 m is 300 cm, the same as 300 cm.
Common mistakes:
- C · 300 cm: It looks as if you compared the numbers without their units. A bigger number can be a smaller amount when its unit is smaller: write both in the same unit first, then compare.
-
A rectangle is 11 cm long and 8 cm wide.
What is its perimeter?
Show the answer to question 6
Answer: 38 cm
Why:
Perimeter is all the way round: 11 + 8 + 11 + 8 = 38 cm. Or 2 × (11 + 8).
Common mistakes:
- 88: That is the area: the length multiplied by the width. The perimeter is the distance all the way round, so add up every side.
Answers
- 1. B · 7 m
- 2. C · 50 cm
- 3. C · 12:25 am
- 4. 12:20 (also accept 12.20, 1220, 12:20 pm)
- 5. A · They are the same length
- 6. 38 cm
How Remelia uses a mistake
When a wrong answer matches one of these mistakes, the app says what the child seems to have done before they try again, and brings the objective back on a later day.
Remelia practises maths for the child's own year group, in short sessions, and brings back on later days what they got wrong.