few_shots: 
Example:
Concept/skill: 
Prove that, given a system of two equations in two variables, replacing one equation by the sum of that equation and a multiple of the other produces a system with the same solutions.

Problem/activity:
Problem 1
The table below contains single equations in a single variable, single equations in two variables, and pairs of simultaneous equations in two variables. Check the appropriate box to show whether there is no solution, exactly 1 solution, or if there is an infinite number of solutions.
|                                                          | **           No solution          ** | **           Exactly 1 solution          ** | **           Infinite number of solutions          ** |
|----------------------------------------------------------|--------------------------------------|---------------------------------------------|-------------------------------------------------------|
|                       $${9=4x+7}$$                       |                                      |                                             |                                                       |
|                       $${y=3y+5}$$                       |                                      |                                             |                                                       |
|                    $${y={x\over2}}$$                     |                                      |                                             |                                                       |
|                     $${3x+6y-9=0}$$                      |                                      |                                             |                                                       |
|    $${x=y}$$                        $${1.25x=1.25y}$$    |                                      |                                             |                                                       |
| $${9.9=6x+8y}$$                        $${9x=2.5y-8.8}$$ |                                      |                                             |                                                       |
| $${11x-2y=1.5}$$                        $${11x-2y=2.5}$$ |                                      |                                             |                                                       |
Problem 2
Kim has a small container and a large container as shown.
[IMG]
It takes 16 of the small containers to fill the large container. Three small containers leave 1.95 gallons of space in the big container.
What is the size of each of the two containers?


Answer: 
No. Completing neither of these problems requires replacing one equation by the sum of that equation and a multiple of the other equation.

Now, determine whether the following problem or activity can enable students to understand the concepts or skills in the provided description.

shot_info: fl_problem_001392_neg_0

8
standard_description: Relate area to the operations of multiplication and addition.
problem_activity: Narrative
The purpose of this activity is for students to see how other students solved one of the problems that involves a factor of a teen number. While students look at each other’s work, they will leave sticky notes describing why they think the answer does or does not make sense (MP3). The synthesis will look specifically at examples of how students used the area diagram to represent the problem.
MLR8 Discussion Supports.
Synthesis: As students share their observations about the selected posters, annotate the poster to illustrate connections. For example, circle the factors and the product and write “factors” and “product” respectively.
Advances: Listening, Representing
Required Materials
Materials to Gather
Sticky notes
Launch
Groups of 2
“Before you begin the gallery walk, what are some representations you expect to see as you look at other students’ work?” (I expect to see rectangles because some of the problems were about the area of rectangles. Base-ten blocks because we were multiplying teen numbers.)
Share responses.
Give students sticky notes.
Activity
“As you visit the posters with your partner, discuss what is the same and what is different about the thinking shown on each poster. Also, leave a sticky note describing why you think the solution does or does not make sense.”
8–10 minutes: gallery walk
Monitor for different uses of the area diagram to highlight, specifically:
a fully gridded area diagram with no labels and no decomposition
a gridded area diagram that was gridded, but also decomposed into parts or labeled along the sides or in the parts of the rectangle
a partitioned rectangle that was drawn with no grid, but labeled with side lengths or the area of the parts of the rectangle
Student Facing
As you visit the posters with your partner, discuss what is the same and what is different about the thinking shown on each poster.
Student Response
Teachers with a valid work email address can
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Activity Synthesis
Select 2–3 posters that used a diagram to represent the problem. Discuss them in the order shown above.
For each poster, ask:
“How are the factors shown in the diagram?”
“How is the product shown in the diagram?”
“How could we represent this strategy with expressions?”
If students don’t use an ungridded diagram, display one that represents the problems and ask the same questions.
[IMG]


aligns: no