In grade 1, students measure things using non-standard units. To help students with their understanding, teachers should know why they need to do this and some fundamental principles of developing measuring skills.
1. Using non-standard units helps students focus on the attribute being measured. For this reason, the non-standard unit should possess and suggest the attribute. If you’re measuring length, what you use to measure it should suggest length.
Many lessons have their students use their hands as non-standard units to measure length. Students sometimes think of area when they use their hands, as they cover things with their hands more often than they compare lengths. Length is implied however, so it’s not really a poor unit. The child’s feet might be better though.
2. Making Rulers
Many difficulties in later years are due to the fact that students really don’t know how a ruler is constructed, or what it’s really doing. You can find clarification on this in the grade 2 section (not complete yet).
Due to this, a general principle is that students should always construct their own measuring tools before using standard ones. This means that in grade 1, if you measure using non-standard units then you should get around to making rulers for non-standard units.
Rather than continuing to iterate their hands across various objects, they need to trace their hands in stacks on something like butcher block paper and use this to measure items.
Using a ruler like this, they can measure things around the room.
Other rulers they can make:
Stacks of cubes.
Stamps on a roll of cash register tape, usually available quite cheaply from any stationary store.
3. Transitive Reasoning
I’ve seen activities in popular programs where students measure the length of a variety of things using hands or paperclips, to no apparent purpose.
I’d much rather see purpose driven measurement, and this would also explore transitive reasoning. Basically, we should measure things things when we cannot compare them directly – otherwise we’d just line them up.
A good problem solving format might be:
We need to move this table to the gym for a dance. Do you think it will fit?
The other class says they have larger desks – how can we check?