Reflection: Intervention and Extension Going Mental over Percents - Section 2: Warm up


I can get a lot of information about what my students do and do not know when they draw diagrams and models. I know that my students can get the right answer and still have a very fragile understanding of a concept. Their misconceptions sometimes present themselves more clearly in their diagrams and models. Especially with my students who have trouble articulating their thinking it is easier to surface a misconception and have a conversation about it when there is a visual model to refer to.

When I saw how a pair of my students had modeled their strategies, I saw a circle divided into 5 parts, but those parts were clearly not equal. I didn't know if the problem was a conceptual one or an artistic one (since it is not easy to divide a circle into an odd number of equal parts). When I asked Cristina and Angelina to explain their diagram they clearly understood that the parts were supposed to be equal and just had trouble drawing it correctly. However, as they continued to explain their diagram, it became evident they needed help thinking about the whole (circle) as both five (equal parts) AND 20 (dollars). 

Don't be afraid to ask a student to explain a model that doesn't make sense to you. The conversation will either help the student clarify their understanding or it will help you (and the rest of the class) see another way of thinking about it. When I asked about this one, I realized it was just a set model which I didn't expect anyone to use, but I didn't see it at first until the student explained it. 

  Intervention and Extension: Keep on the lookout for misconceptions
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Going Mental over Percents

Unit 8: Exploring Rational Numbers
Lesson 20 of 20

Objective: Students will be able to explain multiple methods for mental calculation of a percent increase or decrease.

Big Idea: Exposure to multiple methods makes students more flexible and more confident problem solvers, helping them persevere when they get stuck.

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1 teacher likes this lesson
Math, modeling, Number Sense and Operations, context, number talk, mental math, perseverance, percent increase and decrease, percent, calculation strategies, rational numbers
  54 minutes
drawing a model of mental calculation
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