Thursday
Thursday: The acorn piles
Chris the Coyote settles by the campfire stones and adjusts the feather in his hat.
"Last autumn, Oliver counted the acorns in two great piles," he says.
"One pile had 1,894 acorns. The other had 921."
"Then Riley the Raccoon asked, what if we had three times as many acorns?"
"Riley started to add and multiply, his tail swishing busily."
"Oliver simply wrote 3 × (1,894 + 921) on a leaf."
"No need to calculate," said Oliver. "This is three times the size of both piles together."
Learn it: read an expression without working it out
1,894 + 921 is the number of acorns in both piles.
3 × (1,894 + 921) is 3 times as large as 1,894 + 921.
(1,894 + 921) ÷ 2 is half as large.
(1,894 + 921) + 10 is 10 more.
We can compare expressions like these without working them out.
The picture shows 3 × 6. It is 3 times as large as one group of 6.
- Read the question.
- Tap your answer.
- Read the question.
- Tap your answer.
- Read the question.
- Tap your answer.
| Sentence | True or false? |
|---|---|
| 3 × (1,894 + 921) is 3 times as large as 1,894 + 921. | ? |
| (500 + 60) ÷ 2 is twice as large as 500 + 60. | ? |
| (45 + 30) + 10 is 10 more than 45 + 30. | ? |
| 3 × (20 + 5) = 75 | ? |
Write an expression for twice as many, like 2 × (8 + 5).
Write an expression for half as many, if the number can be split in half.
Tell a grown-up what each expression means, without working it out.
What a story! Tomorrow Freddy has an expression game.