Reflection: Discourse and Questioning What Were They Thinking?! - Section 4: Generalizing

 

When I asked students to describe what is happening mathematically in the strategies that used the identity property they always have an intuitive sense about the reason, but most will not say that it's just like adding zero, most of them won't mention zero. I am always tempted to just tell students what I want them to notice, but I feel it is important to resist that temptation. I want to tell them less and have them figure out more for themselves. Instead of telling them I use questions to turn the thinking back over to them.

When students don't describe the zero in the identity property I ask what this strategy might look like on 27 + 45 and have a student or two lead me through different ways it may look depending upon which of the numbers is changed to a "friendly" number. I circle the additive inverses and ask "if I add 3 and then subtract 3, what am I really adding?" "If I add 5 and then subtract 5 what am I really adding?" If they say "nothing" instead of zero I ask "what's the number for nothing?"

 

  Questioning to scaffold
  Discourse and Questioning: Questioning to scaffold
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What Were They Thinking?!

Unit 1: Order of operations & Number properties
Lesson 8 of 9

Objective: SWBAT describe the various mental math strategies demonstrated by classmates and begin to understand the properties behind them.

Big Idea: Students will start to generalize a variety of strategies to uncover the number properties of addition.

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Subject(s):
Math, commutative property of addition, associative property of addition, Number Sense and Operations, Operations and Expressions, identity property of addition, Mental Math, additive identity, number talk
  54 minutes
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