The most common mistake
Children often start measuring from the end of the ruler, or from 1. On the printed-ruler sheets every object starts exactly at zero; on the “use your own” sheets they have to line it up themselves.
Real size
Every sheet is drawn to scale, so the objects are as long on paper as their measurements say. That makes it easy to check an answer with a real ruler.
Provincial curriculum links
- BC K–1Comparing lengths directly, then measuring with non-standard units from a common baseline.
- BC Grade 2Measuring length, height and width in centimetres and metres.
- ON Grade 1–2Comparing lengths in Grade 1, then using rulers to measure lengths accurately in Grade 2.
- ON Grade 4How the units of the metric system relate to each other.
Canadian schools measure in metric, so centimetres are the unit to choose for class sets. Inches still turn up at home, in heights and screen sizes, so the inch setting is better as a talking point than as the main lesson.
BC’s Kindergarten and Grade 1 content stresses a baseline: lining objects up from the same starting point before comparing them. Measuring with a ruler from zero is that same idea in standard units, which makes the “use your own ruler” sheets a natural Grade 2 task in either province.
Summarized in our own words from the BC Mathematics curriculum (K–2) and Ontario’s overview of The Ontario Curriculum, Grades 1–8: Mathematics (2020).
