few_shots: 
Example 1:
Problem/activity:
You’re mixing ingredients for cookies. The recipe says to combine 6 tablespoons, or ¾ stick, of butter with 1 cup of sugar. You accidentally mix in a whole stick of butter (8 tablespoons) with the cup of sugar. How can you fix this?


Concept/skill: 
Use ratio and rate reasoning to solve real-world and mathematical problems, e.g., by reasoning about tables of equivalent ratios, tape diagrams, double number line diagrams, or equations.

Answer: 
Yes. This problem solves a real-world problem involving mixing ingredients for cookies. A student doing this problem would need to reason about equivalent ratios of butter amounts to sugar amounts.

Example 2:
Problem/activity:
For each pair of numbers, determine if the values are equivalent. Explain your reasoning for each one.
a.
$$-0.25$$
and
$$\frac{1}{-4}$$
b.
$$-\left ( \frac{1}{4} \right )$$
and
$$\frac{-1}{-4}$$
c.
$$\frac{-1}{4}$$
and
$$-\frac{1}{4}$$


Concept/skill: 
Apply and extend previous understandings of multiplication to multiply a fraction or whole number by a fraction.

Answer: 
No. The expressions shown in this problem do not involve multiplying fractions with other fractions, nor whole numbers with fractions.

Example 3:
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?


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.

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, does the problem or activity shown below enable students to learn the full intent of the following concept or skill?

shot_info: fl_problem_000972_pos_0

6

fl_problem_001097_neg_0

7

fl_problem_001392_neg_0

8
standard_description: Use multiplication and division within 100 to solve word problems in situations involving equal groups, arrays, and measurement quantities, e.g., by using drawings and equations with a symbol for the unknown number to represent the problem.
problem_activity: Narrative
Previously, students multiplied two factors where one factor was a whole number and the other a teen number. The purpose of this activity is for students to make sense of multiplication of a one-digit number and a two-digit number greater than 20. Students analyze representations used to find
\(4 \times 23\)
and articulate reasons for using strategies that are based on the distributive property and place value to find products (MP7). Along the way, they see that decomposing the two-digit factors into tens and ones is particularly helpful for multiplying. They also reinforce what they know about the connections between area diagrams and multiplication expressions.
MLR8 Discussion Supports.
Before partner work, remind students to use words such as decompose, tens, and ones.
Advances: Speaking, Representing
Required Materials
Materials to Gather
Base-ten blocks
Materials to Copy
Centimeter Grid Paper - Standard
Launch
Groups of 2
“Take a minute to make sense of how Clare and Andre represented
\(4 \times 23\)
.”
1 minute: quiet think time
Give students access to grid paper and base-ten blocks.
Activity
“Now, work with your partner to complete the first two problems about
\(4 \times 23\)
.”
8–10 minutes: partner work time
Monitor for the diagrams that students choose in Diego’s problem and for their explanations.
Pause for a discussion. Invite students to share their responses.
If not mentioned by students, clarify that all diagrams can be used to multiply 4 and 23, but not all are equally practical.
Select a student to explain why diagram D might be more productive than the other diagrams.
“Now, work independently to complete the last problem.”
2–3 minutes: independent work time
Student Facing
Here is how Clare and Andre represented
\(4 \times 23\)
.
Clare
[IMG]
Andre
[IMG]
How does each diagram show
\(4 \times 23\)
?
How could we use Clare’s diagram to find the value of
\(4 \times 23\)
?
How could we use Andre’s diagram to find the value of
\(4 \times 23\)
?
Diego tried different ways to partition or split a diagram to help him find the value of
\(4 \times 23\)
.
A
[IMG]
B
[IMG]
C
[IMG]
D
[IMG]
What do you notice about the numbers in his diagrams?
Which diagram would you use to find the value of
\(4 \times 23\)
? Explain your reasoning.
Find the value of
\(3 \times 28\)
.
Show your thinking using diagrams, symbols, or other representations.
Student Response
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for free access to Student Response.
Advancing Student Thinking
If students choose a diagram in the second problem that doesn't help them find the product of
\(4\times23\)
, consider asking:
“Tell me about how you chose which diagram you would use to find the value of
\(4\times23\)
.”
“Is there another diagram that would make finding the value of
\(4\times23\)
easier? How would it make it easier?”
Activity Synthesis
“What representations did you use in the last question to show
\(3 \times 28\)
? How did they help you find the product?” (Base-ten blocks helped me break the 28 into tens and ones. A diagram with a grid helped me break 28 into smaller numbers. A diagram with no grid helped me think about the numbers as I labeled it without worrying about all the little squares.)


aligns: no