|
|
Post by gotranch on Nov 19, 2014 7:24:17 GMT
It's a strategy - not a trick. My first graders are learning to add one/minus one to problem solve.
|
|
|
|
Post by monklady123 on Nov 19, 2014 10:20:59 GMT
It's killing me that so many are calling it a "Trick" - it's an actual math skill called decomposition. Taking apart (decomposing) a number. There is nothing "tricky" about it. 5000 - 1847 = 4999 + 1 - 1847 = 4999 - 1847 + 1 It's just breaking the numbers apart into numbers that are easier to work with and using the commutative property to rearrange them. (Though when first teaching it I would make sure they realize it's 5000 + 1 + (-1847) that allows them to change the order to 5000 + (-1847) + 1) I've seen kids do it like this: 5000 - 1847 = 2000 - 1847 + 3000 (find the closest 1000) 1900 - 1847 + 3000 + 100 (find the closest 100) 1850 - 1847 + 3000 + 100 + 50 (find the closest 10) 3 + 3000 + 100 + 50 = 3153 See, this is what I mean? My former district started using this method. And I absolutely hate it. The children have absolutely, positively no idea about place values when math is taught like this in my experience. We have had parents go as far as starting a petition to get rid of this method. It may work for older kids, but it does NOT work in first grade! I firmly believe in teaching number sense, but this method is simply not it in my experience with young kids. Don't get me started on the "new" way to multiply and divide. The entire Everyday Mathematics curriculum is not my friend! Indeed it may not be appropriate for 1st grade, but since my original post was about 3rd grade (which, given the kindergarten curriculum, I think *is* "older kids") I can't comment on that.  5000 - 1847 is the same problem as 4999 - 1846, as well..it is not a trick but understanding that subtraction is also a measure of distance between two numbers. Most of my students add up...1847 + 153 = 2000 and 3000 more get you to 5000..so 3153 This strategy (adding up or distance model) can be VERY helpful when they are subtracting fractions later!! At the risk of getting myself into math over my head   can you explain how this strategy could be useful with fractions? I've never thought of subtraction as a "measure of distance between two numbers"....very interesting. And, I'm sorry I used the word "trick" in my original post. I see now that it is a strategy for working with numbers. I'm glad schools are teaching it. For me, someone who is very bad at math, anything that makes some math thing easier is a trick because it's like I've "tricked" my brain into understanding.  Yeah, I need a remedial course. |
|
|
|
Post by worrywart on Nov 23, 2014 13:13:08 GMT
I'm super late to this post but here is an example of a fraction problem that this would be a good strategy for....say
3 3/8 - 1 7/8 to keep it simple, would be a typical subtraction with regroup/borrowing problem.
So one method would be draw a quick number line, put 1 7/8 on the left and 3 3/8 on the right and count up. 1/8 to get to 2 wholes and 1 3/8 to get to 3 3/8 so the answer is 1/8 plus 1 3/8 (1 1/2). (some students can also do this with mental math)
I teach sixth grade and used to spend three days trying to teach the concept of fraction borrowing to students who really struggled so using a distance model has been very helpful for a lot of students.
The ideas of how far from one fraction to another like from 3/8 to 1 whole is 5/8 is a concept that even the early grades should be focusing on. It takes some of the mystery out of fractions, hopefully!
|
|
can you explain how this strategy could be useful with fractions? I've never thought of subtraction as a "measure of distance between two numbers"....very interesting.
Yeah, I need a remedial course.