The screen says one thing and your head says another. A quick estimate tells you which one to trust.
Not started yet.
By the end of this lesson your student should be able to estimate with decimals by rounding, by clustering and by patterns, and use the estimate to decide whether an exact answer is reasonable.
None of the three tools is new. Rounding and patterns came in U1-L2 and U1-L3 with whole numbers, and this lesson carries them over to decimals.
🚨 Students round every number to the nearest whole number out of habit. The book's rule is the greatest place value: 34.9 rounds to 30, not 35, when you're estimating a product.
Clustering only works when the numbers really do sit near one value. Six numbers between 27 and 35 cluster around 30; a list with 3 and 300 in it doesn't cluster at all.
Give the student a real receipt and a calculator. Have him estimate the total first, then check it, and talk about how close the two came.
Then deliberately mistype one price and see whether the estimate catches it. That's the whole reason for the lesson.
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Before You Start
The words this lesson uses. Tap a card to see what it means, then come back to them whenever a question uses one.
Part One
Questions about the story you just read. Pick your answer straight off, or press Find it in the story if you would rather hunt for the sentence first.
Part Two
The word cards are at the top of this page. Look back at them as often as you need, then answer.