To subtract integers using Algebra Tiles make sure you have the small one unit squares cut out.
It is a good idea to have 2 sets cut out or 54 squares. Remember, the colored side is the POSITIVE quantity and the blank, back side represents the NEGATIVE quantity.
|Click HERE to get your set of Algebra Tiles.|
|Once again, the trick to using algebra tiles to subtract integers is to make ZEROS.||
"zero" is made by placing a positive (colored tile) beside a
negative (plain tile).
|Let's say you have 3 and you want to subtract 4, or ( 3 - 4 = ? )||Well, you could think of the subtraction problem as an "addition of the opposite" problem or 3 + (-4) = ? and then just use the addition approach.|
|OR you could use this rather interesting approach.||Start with three positive tiles and try to physically remove four tiles.|
you say. ....Not really. If we add a zero, it can be done. (remember, adding
zero does not change the value of anything)
Zero and three more still equals three. However, now there are four positive tiles that can be removed!!!
When we pull the four
positive tiles off, we will be left with our answer, -1.
|3 - 4 = -1|
Let's try a harder
Start with five positive tiles and try to subtract seven negatives......
Once again, you say,"It can't be done!" and we say, "ADD SEVEN ZEROS AND then IT CAN BE DONE!"
||Seven zeros plus five still equals five, but now we can pull off seven negative tiles and what we are left with will be the answer.|
|So you see 5 - (-7) = 12. You can actually TOUCH the problem!|
Now you try a few more on your own.
You can always check
your answers on a calculator.
|Have fun "touching" those integer problems.|
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