Year 6 measurement: six questions and the common mistakes

Six questions

1. Convert 930 g into kg.

   Show the answer to question 1

   Answer: 0.93 kg

   Why:

   1,000 g = 1 kg, so 930 ÷ 1,000 = 0.93 kg.

   Common mistakes:

   • 930,000: 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.
   • 9.3: Your digits are right, but in the wrong columns: your answer is 10 times too big.
   • 0.093: Your digits are right, but in the wrong columns: your answer is 10 times too small.

2. 8.3 m is 8 m and how many centimetres?

   Show the answer to question 2

   Answer: 30 cm (also accept 8 m 30 cm, 8 m and 30 cm)

   Why:

   The 8 m is the whole part; 0.3 m is what is left. 1 m = 100 cm, so 0.3 × 100 = 30 cm.

   So 8.3 m is 8 m 30 cm.

   Common mistakes:

   • 3: 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.

3. A flower bed shaped like a parallelogram has a base of 10 m.

   Its perpendicular height is 2 m, and its sloping sides are 4 m long.

   What is its area?

   Show the answer to question 3

   Answer: 20 m²

   Why:

   Area of a parallelogram = base × perpendicular height = 10 × 2 = 20 m².

   The sloping side (4 m) is not needed: it does not meet the base at a right angle.

   Common mistakes:

   • 40: It looks as if you multiplied the base by the sloping side. The area of a parallelogram uses the perpendicular height: the length that meets the base at a right angle.

4. Convert 52.1 km into m.

   Show the answer to question 4

   Answer: 52,100 m

   Why:

   1 km = 1,000 m, so 52.1 × 1,000 = 52,100 m.

   Common mistakes:

   • 0.0521: 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.
   • 521,000: Your digits are right, but in the wrong columns: your answer is 10 times too big.
   • 5,210: Your digits are right, but in the wrong columns: your answer is 10 times too small.

5. Convert 921 mm into m.

   Show the answer to question 5

   Answer: 0.921 m

   Why:

   1,000 mm = 1 m, so 921 ÷ 1,000 = 0.921 m.

   Common mistakes:

   • 921,000: 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.
   • 9.21: Your digits are right, but in the wrong columns: your answer is 10 times too big.
   • 0.0921: Your digits are right, but in the wrong columns: your answer is 10 times too small.

6. 24.2 litres is 24 litres and how many millilitres?

   Show the answer to question 6

   Answer: 200 ml (also accept 24 litres 200 ml, 24 litres and 200 ml)

   Why:

   The 24 litres is the whole part; 0.2 litres is what is left. 1 litre = 1,000 ml, so 0.2 × 1,000 = 200 ml.

   So 24.2 litres is 24 litres 200 ml.

   Common mistakes:

   • 2: 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.