What is length?
Length is how long or tall something is. It is usually measured in millimetres (mm), centimetres (cm) or metres (m).
When we measure small objects, we normally measure in millimetres (mm) or centimetres (cm). A ruler can be used to measure small objects.
When we measure big objects, we normally measure in metres (m).
Let’s practise adding and subtracting in metres, centimetres and millimetres.
2 m + 7 m = 9 m
8 cm − 2 cm = 6 cm
10 mm − 7 mm = 3 mm