Estimating Lengths
Estimate lengths using units of inches, feet, centimetres, and metres
What a learner can do afterwards
- Estimate the length of a classroom object before measuring it
- Use a known reference (e.g. width of a finger ≈ 1 cm) to make reasonable estimates
- Check estimates by measuring and evaluate how close they were
1 · Read
An estimate is a smart guess. Before you measure something, look at it and think about how long it might be. You already know about inches, feet, centimetres, and metres from measuring with a ruler. Estimating means using that knowledge to guess first, then check.
Ben looks at the classroom door before he measures it. He knows he is about 1 metre tall, so he pictures two of himself stacked up. He guesses the door is 2 metres tall. When he measures with a tape, the door really is 2 metres. His estimate was right on target.
Use things you know like a ruler in your head. A finger is about 1 centimetre wide. A big step is about 1 metre long. A sheet of paper is about 1 foot long. Compare the object to something you know before you guess a number.
Look at the object, compare it to something you know, guess a number, then measure to check.
2 · Watch
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Where it sits
Learn first
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Where this leads
17 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.