I have a 3rd grader who is struggling with the concept of subtraction. He has tried number lines which he hates to use, says it makes him feel like a baby and also we have tried the concept of "counting up", but he claims he get confused because it is "take away" not adding. What can I do to help him with this concept? He has an easier time with 8 − 2 but when it is 14 − 3 we run into difficulty. I have even resolved to letting him use the calculator. Any suggestions?
I think he needs to understand the concept of subtraction better, first of all.
My book Subtraction 1 deals with the subtraction concept itself and the three ways it is used:
- take away
- difference
- whole/part
He needs to understand those three ways it is needed. It's not "just" for take-away situations.
Secondly, he needs to realize that addition and subtraction are opposite operations, and THAT IS WHY we use addition facts when doing subtraction problems.
After that link is CEMENTED, he will then learn his addition facts such as 5 + 6 = 11 and 7 + 8 = 15 and then learn to use those with subtraction.
My book Add & Subtract 2-A deals with that part.
That's not all there is to it, of course. With a problem such as 14 − 3, we realize first that it won't "change the ten", then we can use our knowledge of 4 − 3 = 1 to solve tat 14 − 3 = 11. So understanding this depends also of his understanding of place value (tens and ones).
Hope that helps.
No comments:
Post a Comment