Spider-Man reminded us today that we must begin at the Origin. To begin this lesson I wrote the problem -2 x -3 on the board and let the students talk amungst themselves to come up with the answer. A majority were guessing and applying the rules of addition and subtraction. The answers that were shared were 6 and -6.
I did not want to tell the students the rule first, really wanted them to figure it out on their own.
Spider-Man told us that we had to look carefully at the signs of each integer in the problem. He said if the first integer is negative you must turn toward the negative side of the number line. If the first integer is positive then you must face the positive side. Remember you are standing at the Origin. So basically, the first integer tells you to look left or look right. The second integer tells you to walk forward or backwards. If it is positive you will walk forward, if it is negative you will walk backwards.
For the example -2 x 3. Spider-Man turned to the left, and then he moved forward 2 groups of 3, which is 6, to land on -6.
After we tried a few together with the number line students started to see the rules. So we wrote them on the board. I really like being able to share the "Why" behind the math.
When the signs match that is good, and good is a positive word. When the signs do not match that is bad, and bad is a negative word.
I did not want to tell the students the rule first, really wanted them to figure it out on their own.
Spider-Man told us that we had to look carefully at the signs of each integer in the problem. He said if the first integer is negative you must turn toward the negative side of the number line. If the first integer is positive then you must face the positive side. Remember you are standing at the Origin. So basically, the first integer tells you to look left or look right. The second integer tells you to walk forward or backwards. If it is positive you will walk forward, if it is negative you will walk backwards.
For the example -2 x 3. Spider-Man turned to the left, and then he moved forward 2 groups of 3, which is 6, to land on -6.
After we tried a few together with the number line students started to see the rules. So we wrote them on the board. I really like being able to share the "Why" behind the math.
When the signs match that is good, and good is a positive word. When the signs do not match that is bad, and bad is a negative word.
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