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 to multiply a fraction or whole number by a fraction.

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

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_neg_0

7

fl_problem_001392_neg_0

8
standard_description: Write an inequality of the form x > c or x < c to represent a constraint or condition in a real-world or mathematical problem. Recognize that inequalities of the form x > c or x < c have infinitely many solutions; represent solutions of such inequalities on number line diagrams.
problem_activity: Problem 1
Sarita has a fish tank in the shape of a rectangular prism. The bottom of the fish tank measures
$${10}$$
inches by
$$8$$
inches. Sarita wants to add some sand to cover the bottom of the tank, and she uses the formula
$${ V=l × w × h}$$
to determine the volume of sand she needs.
a.   If the height of the sand measures
$$2$$
inches, what is the volume of sand needed?
b.   If the height of the sand measures
$${3.5}$$
inches, what is the volume of sand needed?
c.   Sarita cannot decide how high she wants the sand to be in the tank. What expression can she use to represent the volume of sand needed for
any
height of sand?
Problem 2
In each example, write an expression to represent the quantity.
a.   Thomas is
$$x$$
years old.
His sister is
$$5$$
years older. How old is his sister?
His dog is
$$3$$
years younger. How old is his dog?
His cousin is
$${3\over4}$$
his age. How old is his cousin?
His friend is
$$y$$
years younger. How old is his friend?
b.   Reina has
$$5$$
more quarters than dimes.
She has
$$8$$
dimes. How many quarters does she have?
She has
$$15$$
quarters. How many dimes does she have?
She has
$$d$$
dimes. How many quarters does she have?
She has
$$q$$
quarters. How many dimes does she have?
Problem 3
a.   A numeric expression like
$${5+(8+2)^2}$$
has one and only one value. What is it?
b.   Consider the expression
$${ {5+(x+2)^2}}$$
. What are some values it can have? Make sure you organize your work so anyone can tell which value for the expression goes with which
$$x$$
value.
c.   How many different values can an algebraic expression like
$${5+(x+2)^2}$$
have?


aligns: no