Measuring length (age 6+)
Measure the length of an object using same-size length units laid end to end with no gaps or overlaps
What a learner can do afterwards
- Measure a book by laying paper clips end to end and counting them
- Understand that the length measurement is the number of units that span the object
- Avoid gaps and overlaps when placing units
1 · Read
You already know how to tell which of two things is longer. To measure exactly how long something is, use small units that are all the same size, like paper clips or blocks. Lay them in a straight line, end to end, so they touch but do not overlap or leave gaps.
Sam measures his book by lining up 8 identical blocks along its edge, end to end, with no gaps. He counts them one by one: 1, 2, 3, 4, 5, 6, 7, 8. The book is 8 blocks long. Gaps would leave some length with no block, so the count would be too small. Overlaps would cover some length twice, so the count would be too big.
If you leave a gap between blocks, some length never gets counted, so your count is too small. If your blocks overlap, you use more of them than you need, so your count is too big.
Line up same-size units end to end, with no gaps or overlaps, then count them. That count is the length.
2 · Watch
Take it off screen
Where it sits
Where this leads
18 questions wait behind this lesson, each with its answer explained. Every answer feeds the sky: stars light as they are learned, and dim when it is time to come back.