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mrwalpole mrwalpole is offline
 
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Help!
Old 09-26-2012, 03:14 PM
 
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My students are struggling with subtraction (have been for years and their MCAS scores show this). I want to do a subtraction lesson that could really hit home. Any ideas?

Also I want to dedicate Fridays to word problem solving day. Any idea on where to get great problems.

Thanks!


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Old 09-26-2012, 03:19 PM
 
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Evan Moor publishes a Daily Word Problem book that has really good problems.
What exactly are they struggling with? Remembering basic facts or regrouping or something else?
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regrouping
Old 09-26-2012, 03:45 PM
 
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for example

43
- 28

They would say 25....I am struggling on what to do!
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borrow some base ten blocks
Old 09-26-2012, 03:48 PM
 
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I think they need that connecting level where they use manipulatives along with the written numbers. 2nd grade should have base ten blocks for you to borrow, or even 1st grade (we only use 10s and ones, and you'll need the hundreds, too.

Once they see what the numbers stand for, it should click. You need to take it down a notch.
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Base 10 + Number Grid
Old 09-26-2012, 06:37 PM
 
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You definitely need to do hands-on activities. In addition to the base ten blocks, model subtraction on a number grid (hundreds chart). For my students that really struggle, I give them highlighting tape. So for 43-28, they would highlight those two numbers and count how many "hops" they took in between. Or you can show them how to start at 43 and take 28 hops backwards.

You can tie this is with the base ten blocks because when you move up or down on the number grid, you count by ten (like a "long" in base 10 blocks) and when you move across on the number grid, you count by ones (like a "cube" in base 10 blocks).

Then you can move into the various algorithms for subtraction once they have a solid understanding of what subtraction really means.


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Two things
Old 09-26-2012, 08:36 PM
 
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I have done to teach the subtraction algorithm (after working with the manipulatives) are to teach the kids an acronym for the steps. I use GRASS
G= "get a grip" Do I need to regroup or can I just subtract? (I teach "bigger bottom, better borrow" to help them decide this.) If the bottom number is bigger then
R = regroup
A= add the ten the one's place
S= subtract
S= step to the left and start the process again

I also use a website - dositey.com they have an interactive lesson that walks the kids through regrouping one step at a time and gives many problems to practice.
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love this site ...for everything
Old 09-26-2012, 09:22 PM
 
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K-5 Math Teaching Resources; has LOTS of freebies, but i purchased the Math Journal pack for $7 and was well worth it. Problem solving questions for all domains; encourages writing, collaboration, those "AH HA" moments we teachers love when they work through problems.

http://www.k-5mathteachingresources....-journals.html

I recently got their Common Core Vocabulary since we are starting that next year. However, this year, I use what they have on their site and it is extensive. Lots of math games for centers for subtraction too!
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Old 09-27-2012, 12:15 PM
 
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I strongly feel that having them use a place value mat with manipulatives (digi blocks, colored counters , base ten blocks) to show that they can nnot take away 8 from 3. This will help them visualize the skill.
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Old 09-27-2012, 02:06 PM
 
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I agree with previous posts to visualize the concept-I felt like that helped my strugglers a lot last year. We also chanted "bigger bottom better borrow"-so like your previous example I would say 8 is bigger than 3-it's a bigger bottom so I better borrow. It' made the kids laugh and they liked it so they said it-It helped us. Good Luck!!!
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