measurement · Year 3 · AC9M3M02
Reading a ruler
The length of an object is how many centimetre spaces it covers on the ruler, not how many lines it touches. When one end sits exactly on the 0 mark, the number at the other end is the length. When the object does not start at 0, take the starting number away from the finishing number. From 2 cm to 8 cm is 8 − 2 = 6 cm, because there are six one-centimetre spaces in between.
Sample questions
A matchstick starts at 0 cm and ends at 7 cm on the ruler. How long is it (in cm)?
- The matchstick runs from the 0 cm mark to the 7 cm mark.
- Count the spaces, not the marks: 7 − 0 = 7 cm.
Answer: 7
A matchstick starts at 0 cm and ends at 6 cm on the ruler. How long is it (in cm)?
- The matchstick runs from the 0 cm mark to the 6 cm mark.
- Count the spaces, not the marks: 6 − 0 = 6 cm.
Answer: 6
A ribbon starts at 0 cm and ends at 7 cm on the ruler. How long is it (in cm)?
- The ribbon runs from the 0 cm mark to the 7 cm mark.
- Count the spaces, not the marks: 7 − 0 = 7 cm.
Answer: 7