RemeliaMaths Year 5 Measurement
Year 5 converting metric units
The objective: Convert between different units of metric measure (km/m; cm/m; cm/mm; g/kg; l/ml).
The explanation, example and questions are the ones Remelia uses in the app; the questions are not taken from any test paper.
The idea
Every metric conversion is a multiply or divide by 10, 100 or 1000. Which one, and which direction, is all there is to it.
How to do it
- 1 km = 1000 m. 1 m = 100 cm. 1 cm = 10 mm. 1 kg = 1000 g. 1 l = 1000 ml.
- Bigger unit to smaller: multiply, and the number gets bigger.
- Smaller to bigger: divide.
A worked example
3.4 km = 3.4 × 1000 = 3400 m. 250 g = 250 ÷ 1000 = 0.25 kg.
Watch for
Going the wrong way. Sanity-check: 2500 m in km must be a smaller number, so 2.5 km.
Try four questions
-
How long is the piece of ribbon, in centimetres?
Show the answer to question 1
Answer: 2 cm
Why:
Each centimetre is split into 10 millimetres. The right end is at 3 cm, which is 30 mm.
The piece of ribbon starts at 1 cm, not at 0. 30 − 10 = 20 mm. 20 mm is 20 ÷ 10 = 2 cm.
-
3.37 litres is 3 litres and how many millilitres?
Show the answer to question 2
Answer: 370 ml (also accept 3 litres 370 ml, 3 litres and 370 ml)
Why:
The 3 litres is the whole part; 0.37 litres is what is left. 1 litre = 1,000 ml, so 0.37 × 1,000 = 370 ml.
So 3.37 litres is 3 litres 370 ml.
-
Convert 0.508 kg into g.
Show the answer to question 3
Answer: 508 g
Why:
1 kg = 1000 g, so multiply: 0.508 × 1000 = 508 g.
-
Which is heavier: 6,930 g or 6.93 kg?
- A They weigh the same
- B 6,930 g
- C 6.93 kg
Show the answer to question 4
Answer: A · They weigh the same
Why:
Put both in the same unit. 6.93 kg is 6,930 g, the same as 6,930 g.
Answers
- 1. 2 cm
- 2. 370 ml (also accept 3 litres 370 ml, 3 litres and 370 ml)
- 3. 508 g
- 4. A · They weigh the same
The mistakes Remelia names
When a wrong answer to a question like these matches one of these mistakes, the app says what the child seems to have done before they try again.
- Question 1, the answer 200: It looks as if you multiplied instead of dividing. Dividing by 10, 100 or 1,000 makes a number smaller: the digits move to the right.
- Question 1, the answer 20: Your digits are right, but in the wrong columns: your answer is 10 times too big.
- Question 1, the answer 0.2: Your digits are right, but in the wrong columns: your answer is 10 times too small.
- Question 2, the answer 37: It looks as if you copied the digits after the decimal point into the smaller unit. Those digits are part of one whole of the bigger unit, so change that part: 0.25 of 1,000 is 250, not 25.
- Question 3, the answer 0.000508: It looks as if you divided instead of multiplying. A smaller unit takes more of them to make the same amount, so the number gets bigger: the digits move to the left.
- Question 4, the answer B · 6,930 g: 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.