Reflection: Discourse and Questioning Decomposing Large Rectangles - Section 2: Student Practice: Part 1


The video, Excited Problem Solving, shows the high level of student engagement during this activity! Students truly took the challenges seriously! Here's a dictation of this video, along with my reflections on this group's conversation:

Student 1: You guys did 10 x 9 which is 90 and I got 45, which is 9 x 5.  This student is correct (10x9) + (5 x9) = (15 x 9) or 135 and is trying to figure out how he can convince his group!

Student 2: No, it would be 95. This student is multiplying (10 x 9 )+ 5.

Student 3: No, you could do 45 x 10.  This student is getting the numbers mixed up and is still trying to understand how to decompose this larger rectangle.

Student 1: This student isn’t giving up! No it wouldn’t be 95, ‘cause think about it… the five has to go nine times. 

Student 4: So that would be 50 x 90. This student is still grasping the idea behind the activity.

Student 2: Dude, look. 1… 2… 3… 4… 5… 6… 7… 8…. 9…. 10… There’s a hundred… no… wait…. wait… there’s 90 right here on the way back. There’s 9 x 10. There’s 10 up here and 9 down here. And then if we added one more it would be… This student is starting to grasp it. 

Student 1: This student decides to try to explain using a different strategy. Five times nine would be (counting on his fingers) 5, 10, 15, 20, 25, 30, 35, 40, 45.

Student 3: RightHe's beginning to catch on.

Student 2: Yeah… no. You’re doing 9 x 5.

Student 1: Yeah, 9 x 5 and then 9 x 10.  So 90 + 45.

Student 2: Starting to get it… Yeah… so… um… one hundred… thirty…

Student 3: 135!

Student 4: He grabbed the paper, making sense of it. I should have given groups more than one paper so that kids who need to be hands-on could have the opportunity. Now we just have to show our work.  

I absolutely loved listening to this conversation. When students participate in mathematical discourse, it gives them the opportunity to accept and provide constructive feedback.

  Discourse and Questioning: Students Collaborating
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Decomposing Large Rectangles

Unit 14: Area & Perimeter
Lesson 7 of 19

Objective: SWBAT use smaller rectangles to find the area of a larger rectangle.

Big Idea: Students will explore how to use smaller rectangles and friendly numbers to find the area of larger rectangles.

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