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Help with 3 digit/4 digit multiplication


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My 4th grade daughter is struggling with 3-digit multiplication and 4-digit multiplication.  She is currently finishing off MathUSee Delta, but i don't want to move on until she is doing multiplication correctly. 

 

I'm thinking of trying out some other math programs. She gets the concept, but I'm concerned about her completing the procedural steps. Am I just overly paranoid? :banghead:

 

Do you have any suggestions on how i can help her?

Is multiplication a difficult topic for a 10 year old? Am I expecting too much?

 

Thanks for reading  :bigear:

 

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I'm not familiar with MUS, but if it is otherwise working for you, I would not necessarily drop it.  

 

Does she understand that 357 x 6 is the same as 300x6 + 50x6 + 7x6 ?

 

Does she understand that 357 x 58 is the same as 357 x 50 + 357x8 ? (and can break those down into partial products as above?)

 

And similar question for 4512 x 218.  

 

If so, and she's just sometimes getting lost in the actual algorithm for a stacked multiplication problem, then I'd just do a few a day until the steps are really cemented into her mind.  I always tell my kids to be sure to erase any "carrying" marks as they move through the problem, or else it's easy to get confused.  

 

The problem with things like the stacked multiplication and long division algorithms is that often times we move on to them before the student REALLY understands partial products and what is happening in long division.  And then, once they get the algorithm, we never review the meaning behind it, so they forget and are then totally dependent on remembering the steps perfectly and can't figure it out otherwise.  

 

So I vote for sticking with it, maybe doing some of the unrelated chapters at half speed in the next book, but really continuing to work on the concept until she's got it.    

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I think you hit the nail on the head.

 

It's not something that she consciously uses

 

 

Does she understand that 357 x 6 is the same as 300x6 + 50x6 + 7x6 ?

 

Does she understand that 357 x 58 is the same as 357 x 50 + 357x8 ? (and can break those down into partial products as above?)

 

And similar question for 4512 x 218.  

 

 

this is a big problem, her numbers and writings are so small that sometimes she gets confused by the steps and easily lose confidence

 

 

If so, and she's just sometimes getting lost in the actual algorithm for a stacked multiplication problem, then I'd just do a few a day until the steps are really cemented into her mind.  I always tell my kids to be sure to erase any "carrying" marks as they move through the problem, or else it's easy to get confused.  

 

The problem with things like the stacked multiplication and long division algorithms is that often times we move on to them before the student REALLY understands partial products and what is happening in long division.  And then, once they get the algorithm, we never review the meaning behind it, so they forget and are then totally dependent on remembering the steps perfectly and can't figure it out otherwise.  

 

So I vote for sticking with it, maybe doing some of the unrelated chapters at half speed in the next book, but really continuing to work on the concept until she's got it.    

 

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I made graph paper for my kid when he was doing MUS.  Long, vertical lines of color in groups of six (red, blue, green, red, blue, green) separated by a white line.  This gave him a work area pretty equal to his MUS page, but the colors helped him see he was multiplying tens by tens or whatnot and seeing it better in his head.

If necessary, I would move her back a few lessons where MUS explicitly teaches it and how to break out the problem from 546 to 500 + 40 + 6 for each line.

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Graph paper. Graph paper. Graph paper. Or at the very least turn a ruled filler paper sideways so the lines make columns instead of rows.

 

And if you still have those base ten blocks around I'd have her physically act out the problems e.v.e.r.y.d.a.y. Until she can very easily explain to you precisely what is happening. If you don't have blocks you can use google something like free base ten blocks printable and print some out for her.

Edited by SilverMoon
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O.k. I agree that graph paper is a good idea but something else that MIGHT help is switching how she writes out the problems completely.  Lattice method worked brilliantly for my DD when she struggled with this.  It was gobbledygook for me at first, but it really clicked for her.  And now I even prefer this method and am much faster at multi-digit multiplication than I ever was using a standard layout.

 

I suggest looking at you tube videos, practicing the method yourself until you are comfortable doing it, then present it to your child and see if they grasp it better than the traditional method.  I will warn you, it may seem like a lot more work but once DD saw it, it made sense to her and once she had done it a few times she can now whip through multi-digit multiplication at a MUCH faster rate and never makes a mistake in layout or place value.  It actually sets up the various processes in a much more logical fashion, with all the multiplication done first, THEN adding, THEN writing out the final answer, instead of fipping back and forth.  I linked a few videos below.  None are great but they get the job done.

 

 

 

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We did a similar method - the montessori checkerboard.  I took a pillowcase and green, blue, pink paints to create the squares (big enough to hold the MUS blocks up to 9).  It's more visual than the lattice on paper.  You can look up a youtube of how to use the checkerboard exactly but it's pretty easy. 

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We did a similar method - the montessori checkerboard. I took a pillowcase and green, blue, pink paints to create the squares (big enough to hold the MUS blocks up to 9). It's more visual than the lattice on paper. You can look up a youtube of how to use the checkerboard exactly but it's pretty easy.

I'm curious about this. Could you elaborate? Do you use the 1-9 unit blocks in the tens and hundreds squares too? Not the 10 blocks and hundreds flats?

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I'm curious about this. Could you elaborate? Do you use the 1-9 unit blocks in the tens and hundreds squares too? Not the 10 blocks and hundreds flats?

 

Yes, mostly because I needed to be able to show multiplication to the thousands and if I extended the squares another half an inch each they wouldn't fit. :)  The place value squares are all colored on the checkerboard, making it easy to see that even if you have 2 yellow blocks, they're on a blue background and therefore equal 8 tens, not 8.  I was thinking this over last night as I have another kid coming up on it, wondering if I can use a thin doormat from the Dollar Tree to make one that has bigger squares, but I think we would run into the other problem we had still - not having enough tens to complete the equations and reverting to the unit blocks again.

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Last year I built some really big problems with my oldest. Lol. We got more sets of used blocks so we could do it but it took the whole front room floor. This sounds like it would give a similar visual of what's happening but in a more space saving way. How big did you make the squares?

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I wouldn't curriculum switch, especially if other things are clicking. You will just have mores gaps. MUS sequence of topics is especially different than a lot of other math programs. Stop for a few days to review it, but then keep going with a different topic in math while continually reviewing. One of my mistakes was stopping for too long to review a concept and getting too behind. If there's a foundational issue keeping you from going forward, by all means, adjust to their level. But you don't have to stop everything forever until they get one concept. Just keep practicing and don't move on to a topic that it depends on until she gets it down.

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