Compatible numbers? Help!

Discussion in 'Elementary Education' started by giraffe326, Sep 23, 2007.

  1. giraffe326

    giraffe326 Virtuoso

    Jan 2, 2006
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    Sep 23, 2007

    I have been forewarned by my fellow 5th grade teachers that the kids have a very hard time with compatible numbers. Are there any tricks to get them to understand this?? :confused: I will be teaching them on Monday, so any tips are appreciated!

  3. sciencegirl

    sciencegirl Rookie

    Aug 9, 2007
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    Sep 23, 2007

    I taught 5th grade 2 years ago, and found that this wasn't too hard for them. However, last year my 4th graders struggled and struggled with it. I think it comes down to whether or not your kids know their multiplication facts by heart.

    You'll definitely want to be sure you have a multiplication chart hanging up where all kids can see it during the lesson, and I recommend having laminated copies that kids can have at their seats as well, especially during independent practice. I also gave my kids one copy to keep in their homework folders. (The laminated set lived on a common shelf in my room and never went home with the kids.)

    That said, I recommend using different colors and underlining parts of the problem. For example, if you're doing 460 divided by 8, you want to underline in a bright color the numbers 4 and 6 so the number 46 jumps out at them. Then have them use their charts to look along the 8's row in their multiplication chart to find a number as close to 46 as possible. They'll find 48, and you can show them that that is the compatible number. Then remind them they'll need one zero at the end since the original number was 460, not 46.

    Make sense? I think the gist of what I'm saying is be sure to teach them how to use the multiplication chart effectively, and most of all, encourage them to learn these facts by memory because it will make everything so much easier!!
  4. Upsadaisy

    Upsadaisy Moderator

    Aug 2, 2002
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    Sep 23, 2007

    For division, I explain compatible numbers as ways to round so that you have a problem so easy that you can probably do it in your head. For addition, I've heard of teachers in younger grades introducing them as 'friends' numbers.

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