Reflection: Adjustments to Practice Magic Witch Hats - Section 4: Magic Witch Hats


I have to find a different way of facilitating this lesson. I think it was particularly confusing for my students because we had just been working on equivalent expressions. They had been focused on understanding why subtracting was equivalent to 'adding the opposite'. When students ended up with -3 + (-5) next to -3 + (+5) they got confused because they weren't equivalent.

My intention was to cement the idea that addition problems don't need to change and that changing subtraction makes it 'friendlier'. If I had been explicit about my intentions with students or if I had asked them questions like:


  • "Why did I make subtraction the bad witch?" (because it is a harder problem)
  • "In what ways are the good and bad witches the same/different?" (starts with the same number, opposite operation, different answers - not equivalent)
  • "Why do I say every bad witch has a good side?" (because the problem can be exchanged for a 'friendlier' one)
  • "After exchanging the subtraction for addition, how do the two witches compare?" (they are still the opposite)
  • "What two expressions are equivalent?" (the two expressions for the bad witch)
  • "Why did we not have to exchange the good witch's expression?" and "what would it look like if we did?" and "why is that not helpful?"


The second and fourth questions may highlight that the two expressions are still opposite:

  • subtracting negative five is the opposite of adding negative five
  • adding negative five is still the opposite of adding positive five

  This might be too confusing
  Adjustments to Practice: This might be too confusing
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Magic Witch Hats

Unit 4: Operations with Integers
Lesson 17 of 24

Objective: SWBAT add the opposite instead of subtracting integers.

Big Idea: Students will understand that subtracting is like "canceling out".

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Math, Number Sense and Operations, Operations and Expressions, subtracting integers, Additive inverse, halloween, student ownership
  54 minutes
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