A calculator gives you an answer instantly. It won't tell you if that answer is wrong.
Not started yet.
Students will use estimation to decide whether a calculated answer is reasonable, catching the kind of mistake a calculator itself cannot catch.
Build a rough estimate the same way earlier lessons did, by rounding and using patterns, then compare it to the real answer. Close means reasonable; far off means something in the real calculation went wrong.
Jordan's problem is the trap: the calculation itself was set up wrong, since 12 times $0.35 does not equal $42.00, and only the estimate catches it, because the calculator will confidently repeat any mistake it's given.
Type a wrong calculation into a calculator on purpose, in front of him, and have him estimate first to catch it before you reveal the calculator's answer.
Read-aloud is not available in this browser. Try Chrome or Safari.
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.