More often than not, more is less

In the summer, Costco peddles a buttload of educational workbooks. You know the ones: collections of every worksheet necessary for your child to complete <insert grade here> Math. Can’t find them? Look over by the Christmas trees.

I picked up the Grade 3 book. Just browsing. Killing time. I opened to this page:

add:subtract words

I’m not a big fan of this approach. Forget about comprehension, just scan for the add or subtract words. See more, think add. But it’s not that easy. More shows up in five of the practice exercises. Try them.

  • In the picture, how many more 4-legged animals are there than 2-legged ones?
  • Peter has 39 goats.  He wants to have 64 goats.  How many more goats should he buy?
  • Peter has 68 animals on his farm.  He buys 23 more.  How many animals does he have now?
  • 413 gulls are joined by 311 more.  Then 136 more gulls come.  How many gulls are there altogether?
  • There are 576 gulls, but 153 fly away.  Then 283 more leave.  How many gulls remain?

A mountie (really?!) tells kids (Canadian, no doot) to decide on the operation.

mountie

From the answer key:

  • In the picture, how many more 4-legged animals are there than 2-legged ones? 15 − 12 = 3
  • Peter has 39 goats.  He wants to have 64 goats.  How many more goats should he buy? 64 − 39 = 25
  • Peter has 68 animals on his farm.  He buys 23 more.  How many animals does he have now? 68 + 23 = 91
  • 413 gulls are joined by 311 more.  Then 136 more gulls come.  How many gulls are there altogether? 413 + 311 + 136 = 860
  • There are 576 gulls, but 153 fly away.  Then 283 more leave.  How many gulls remain? 576 − 153 − 283 = 140

Subtraction is used to answer three of five questions with this ‘add’ word. Actually, kids will think addition for the first two questions (12 + 3 = 15 and 39 + 25 = 64) but that’s another post.

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2 thoughts on “More often than not, more is less

  1. Great post. I’m also thinking that their shallow interpretation of the word “more” ignores the type of value being added. Young students might not deal with negative numbers frequently, but I do want them to develop the natural intuition that adding a negative value can result in us having less, not more.

    • Thanks, Shaun. You’re right. And I hadn’t thought about it from the “little white lie” angle (e.g., “Kid, you can’t subtract 6 from 4, no matter how hard you try” and later “Let me tell you about integers”). But this example is worse than lying today then telling the (new) truth tomorrow; this is a lie from the get-go.

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