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: Write simple expressions that record calculations with numbers, and interpret numerical expressions without evaluating them. For example, express the calculation “add 8 and 7, then multiply by 2” as 2 × (8 + 7). Recognize that 3 × (18932 + 921) is three times as large as 18932 + 921, without having to calculate the indicated sum or product.
problem_activity: Problem 1
__________ graham crackers are shared equally by __________ people.
a.   Choose numbers to fill in the blanks. You can only use each number once: 2, 3, 5.
b.   Represent the situation with a diagram or drawing.
c.   Explain or show how you know that each person will get the same amount of graham cracker.
Problem 2
Han’s work shows how 3 people could equally share 2 graham crackers.
[IMG]
a.   How do you know that each person gets about the same amount of graham cracker? Explain or show your thinking. Organize it so it can be followed by others.
b.   Draw a diagram to show a different way that 3 people could share 2 graham crackers so each person got about the same amount of graham cracker.
Problem 3
a.   Using the set of cards (cut out from
Template: Equal Shares
), match each representation with a situation and expression. Some situations and expressions will have more than one matching representation.
b.   Choose one set of matched cards.
Show or explain how the diagram(s) and expression represent the number of sandwiches being shared.
Show or explain how the diagram(s) and expression represent the number of people sharing the sandwiches.
How much sandwich does each person get in the situation?


aligns: no