Comparing and measuring

Measuring tells us how long, how heavy or how much something holds. We start by comparing (longer, shorter, heavier, lighter) and then measure using units like centimetres, grams and litres.

Key facts

  • Length: cm, m, km. Mass: g, kg. Capacity: ml, l.
  • Line things up at the same starting point to compare lengths.
  • Read a ruler from 0, not from the end of the ruler.
  • A balance tips down on the heavier side.

Worked examples

Example 1

Which is heavier: 1 kg of feathers or 900 g of stones?

  1. 1 kg = 1000 g.
  2. 1000 g is more than 900 g.
  3. So the feathers are heavier!

Answer: 1 kg of feathers

Example 2

A pencil starts at 0 and ends at 9 on a ruler. How long is it?

  1. It starts at 0, so the length is the number at the end.
  2. 9 cm

Answer: 9 cm