Reflection: Connection to Prior Knowledge Subtracting Integers - How does subtraction relate to addition? - Section 2: Explore


This was the first time I have done this inquiry activity, and it went well.  When we got to the part where students are looking at the problems side by side and trying to make connections - I encouraged all students to just share what they noticed.  I didn't have anyone that was real positive on a definite rule, so I just asked that they share similarities they could find between the two sets of problems - by approaching the problem that way, I was able to get more students to speak out.  They shared things like - in both problems the subtraction changed to addition, the second number became the opposite, you moved the negative sign, etc.  Then I instructed the students to write the problems on top of each other instead of side by side.  I covered up the second term and asked what they saw - they all agreed that the first number stayed the same, but subtraction became addition.  Then I covered the first term and the operation sign, leaving only the second term in view.  Students said - its the opposite.  That was a good segue into the rule that subtracting is the same as adding the opposite.  Then I heard lots of oohs and ahs :)  (I like those - they are generally good!!)

I did have a couple students that were confused, which is to be expected.  I have created a very safe environment where students are comfortable asking questions, so the students did not hesitate to call me over.  In helping them, students found it most beneficial to write the problems on top of one another.  Often times teachers and/or students go through the problem and just change the original - but by being able to see both problems - students could easily identify if they were indeed adding the opposite.

  Inquiry Reflection
  Connection to Prior Knowledge: Inquiry Reflection
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Subtracting Integers - How does subtraction relate to addition?

Unit 4: Operations with Rational Numbers
Lesson 8 of 23

Objective: Students will be able to subtract integers by adding the additive inverse.

Big Idea: Subtraction does not have to be any harder than addition – students will turn all subtraction problems into addition problems and use the rules they have already mastered!

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subtracting integers
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