few_shots: 
Example 1:
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.

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?


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:
Concept/skill: 
Apply and extend previous understandings of multiplication and division and of fractions to multiply and divide rational numbers.

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
$$-\frac{1}{4}$$


Answer: 
Yes. This problem involves understanding fractions and division to divide rational numbers, such as 1, -4, 4, and -1. This problem also involves an understanding of multiplication: if p and q are integers, then -(p/q) = (-p)/q = p/(-q).

Example 3:
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_000972_pos_0

6

fl_problem_001097_pos_0

7

fl_problem_001392_neg_0

8
standard_description: Compute unit rates associated with ratios of fractions, including ratios of lengths, areas and other quantities measured in like or different units. For example, if a person walks 1/2 mile in each 1/4 hour, compute the unit rate as the complex fraction 1/2/1/4 miles per hour, equivalently 2 miles per hour.
problem_activity: Optional activity
This activity gives students more practice writing an equation that represents the proportional relationship examined in a previous lesson: the amount of flour and honey in a recipe. Students can then use their equation to answer additional questions about the situation.
Launch
Tell students that this activity revisits a context from an earlier lesson. Give students quiet work time followed by partner discussion.
Reading: MLR6 Three Reads.
Use this routine to support reading comprehension of the baking situation, without solving it for students. In the first read, students read the prompt with the goal of comprehending the situation (e.g., there is always the same ratio of honey to flour; different days have different numbers of batches). Delay asking students to complete the table. In the second read, ask students to analyze the prompts to understand the mathematical structure by naming quantities. Listen for, and amplify, the two important quantities that vary in relation to each other in this situation:
f
is the number of cups of flour;
h
is the number of tablespoons of honey. After the third read, ask students to brainstorm possible strategies to determine the amount of flour needed if you know how much honey will be used.
Design Principle(s): Support sense-making
Student Facing
A bakery uses 8 tablespoons of honey for every 10 cups of flour to make bread dough. Some days they bake bigger batches and some days they bake smaller batches, but they always use the same ratio of honey to flour.
Complete the table.
If
\(f\)
is the cups of flour needed for
\(h\)
tablespoons of honey, write an equation that relates
\(f\)
and
\(h\)
.
How much flour is needed for 15 tablespoons of honey? 17 tablespoons? Explain or show your reasoning.
| honey (tbsp) | flour (c) |
|--------------|-----------|
|      1       |           |
|      8       |    10     |
|      16      |           |
|      20      |           |
|    \(h\)     |           |
Student Response
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Activity Synthesis
Ask students to compare answers with their partner and discuss their reasoning until they reach an agreement.
Then, invite students to share how they used their equation from question 2 to answer question 3 with the whole class.


aligns: no