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May 9, 2009

Subtraction Ideas!

Recently, we have been learning how to subtract in my classroom. Here are some fun ideas to try to help teach this concept.  It has been said that in Kindergarten, you may need to find 20 different ways to teach one concept!  This is certainly true of addition and subtraction.  And after a while, the ideas start to run dry.  But the kids need to keep on using manipulatives while learning if they are really going to internalize the concept.  So I just try to keep thinking creatively as much as I possibly can to keep it fun and motivating for all of us!
One thing that I always do is use food to teach subtraction.  Here’s how:  In a small group, roll a die.  Everyone gets that number of pieces of cereal.  Then roll a die and have everyone eat that number of pieces and count the ones that are left.   This works great, since there is no chance of counting the ones that have been taken away!   Have the children practice writing that equation (or watch while you write it) before going on to another problem. 
Tip:  You will need two dice; one with larger numbers and one with smaller numbers.  You can make your own by writing with a permanent marker on a blank wooden cube, or simply cover the numbers on a die with a sticker.  Make sure your dice are two different colors. 
Another tip:  Make sure that you have your students show you how many they are going to eat in the palm of their hands before they put them in their mouths!  Otherwise, you will have some children that will find that their answers are different than other children’s answers since they at the wrong amount of cereal.
We also had the kids roll the dice and make a subtraction equation out of it and write it.  Then we had them make pictures to illustrate the equation.  For example, 5 – 2 = 3 might have a picture of five pigs, but two of them are crossed out, etc.
Another thing we have been doing is to act out equations!  The kids really like this.  We do it with both addition and subtraction.  For subtraction, just pick about five kids and have them stand up in a group.  Then pick someone to pretend to be a bee that stings a couple of them. Those that get stung must fall down.  Then write an equation to illustrate what happened.  As an alternative, you could have the kids pretend to be flies, and have another child pretend to be a frog that eats some of them.  Then write an equation.  We have done this sort of thing with the Five Little Ducks song, too.  You just stop the song after each verse and write an equation. The kids can write their own equations on white boards or magnadoodles, if you like.
We like using Ten-Frames also.  You could use egg cartons and cut off the last two egg cups on one end.  Each child should have their own.  Have the children put ten counters in the ten frame so that there is one counter in each spot.  Then roll a die and have the kids take out that many and put them in the lid side of the ten frame.  Then write the equation and have them read it back to you.  Or, have them each write the equation themselves, and then touch the numbers while reading it back.  I like using ten frames so much for addition and subtraction that I bought a set of “Count-Ten” cartons from Cuisenaire.  They look just like plastic egg cartons, but there are only ten spaces.  They are sturdier and cleaner than using egg cartons.  If we wash them out, we can put cereal or other types of treats inside; then just eat and subtract!  To keep this activity fresh, we change the manipulative that we count with.  I have sets of plastic frogs, assorted insects, caterpillars and butterflies, seasonal erasers (like for Christmas or Valentine’s Day), toy soldiers, pirate “booty,” and stuff like that.  The kids love to use the different items to count.  It makes it seem like an entirely new activity.  We use these ten frames to make teen numbers also.  Just have them fill up the ten frame, and then put a few more counters in the lid section, and then count them all.  My kids enjoyed making one of each of the numbers 10-20, and then coloring in that numbered apple on a tree that I gave them.  We used bingo bottles to fill in the apples.  That idea came from, which is Vanessa Levin’s website.  She has some wonderful, fun ideas that can easily be adapted to suit more difficult K concepts.
There is also a printable subtraction lift the flap book with a zoo animal theme on my Musical Math Resource CD.  There is no song for this one, but the kids get to draw zoo-animals on each page, and then learn to read it.  Each zoo animal has been started with traceable lines on each page so that the kids can easily finish the picture.  For example, the body and head of the elephant is already there on the page with dotted lines to trace.  Then, the children just have to add the legs, ears, nose, and tail.  There is also a subtraction song (and an addition song!) on the Musical Math CD.  The kids love the motions to these songs.  They are on DVD also.  
We are going to use a bunch of old stickers to subtract on Monday.  My mom used to teach and she found a box just stuffed with old stickers!  So I cut them into sets of four, five, or six per page, and then threw them into a couple of tubs.  The kids are going to pick a sheet of stickers and stick them down on the paper.  Then they will roll a die to see how many they should cross out.  Then they will count how many are left and write an equation.  I think it will be fun.  We’re going to do the same thing with a bunch of old Creative Memories dye-cuts that someone gave me recently.
If you have some creative ideas for teaching subtraction, I would love to hear them!  Let’s keep these ideas coming, everybody!