Monday, February 08, 2010

Divisibility War

Last week, Alex was working on divisibility rules. Here are the rules we were working on:
  • 2's - if it ends in 0, 2, 4, 6, or 8, it is divisible by 2
  • 3's - add the digits and if they are divisible by 3, the whole number is divisible by 3
  • 4's - if the last 2 digits of a number are divisible by 4, the whole number is divisible by 4
  • 5's - if it ends in 0 or 5, it is divisible by 5
  • 6's - if it is divisible by both 2 & 3, it is divisible by 6
  • 9's - add the digits and if they are divisible by 9, the whole number is divisible by 9
  • 10's - if it ends in 0, it is divisible by 10

I went online and found this Divisibility War game. Basically, I wrote down some of the numbers from their list and dealt us each out 6 cards. We took turns going through the cards and deciding if they were divisible by each of the following: 2, 3, 4, 5, 6, 9, & 10. For every number that it WAS divisible by, we put a marker on the card. At the end of the game we saw who had the most markers.

After we'd played it a couple of times, I changed the rules a bit. Now, if Alex makes a mistake (or I do!), I will challenge her and "get" her point. This makes sure she is really paying attention (and that I am, too).

She has really liked this game and keeps asking to play it. It is a great way to reinforce divisibility rules!


Cindy said...

JUST what we needed around here! Thanks for posting!

Rhonda said...

What a great way to teach those rules. Thank you so much for sharing.

Hopewell said...

lol at your comment on my blog on "strewing" and being a neat freak. Another friend has a nice basket [in fact it's one of those nifty ones that sits on your steps] for "strewing". When she notices there are not getting any looks she brings the basket out at discussion time and shows something at random to get the sparks going again! Another way is a bulletin board with photocopies of covers and a neat little shelf or basket to go with it. I leave ours for a while--then they are neatly stacked on the fireplace hearth.

Robin said...

Dana, I can't remember, do you use Math-U-See? Cade and I use it and love it. I was never taught these simple techniques and they have made division and reducing fractions SO much easier. It's great that you posted it for other folks.

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