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: Use the four operations to solve word problems involving distances, intervals of time, liquid volumes, masses of objects, and money, including problems involving simple fractions or decimals, and problems that require expressing measurements given in a larger unit in terms of a smaller unit. Represent measurement quantities using diagrams such as number line diagrams that feature a measurement scale.
problem_activity: Narrative
In this activity, students compare pairs of numbers with the same number of digits and the same set of digits (for example, 278 and 872, or 1,356 and 3,156). The goal is to elicit the idea that both the placement and the size of the digits matter in determining the value of a number, and that the digits in certain places matter more than others for making comparisons (MP7).
Required Materials
Materials to Gather
Number cards 0–10
Launch
Groups of 3–4
Give each group a set of cards 0–10. Ask students to remove the cards that show 10.
“What three-digit numbers can we make with 5, 7, and 3?” (357, 375, 537, 573, 735, 753)
Activity
“Work with your group to make pairs of numbers using the digits on the cards. First use 3 cards, then 4, then 5, and lastly 6. Compare each pair of numbers.”
“Think about how you go about comparing each pair of numbers.”
5 minutes: group work time
Monitor for students who:
notice that not all digits need to be compared in order to tell which number in a pair is greater
use place-value language in describing the numbers
make two numbers with the same first digit or the same first and second digits
Student Facing
Your teacher will give you a set of cards, each with a single digit, 0–9.
[IMG]
Use the cards for 2, 7, and 8 to make two different three-digit numbers. Use < or > to compare them.
\(\boxed{\phantom{\frac{00}{00}}} \ \boxed{\phantom{\frac{00}{00}}} \ \boxed{\phantom{\frac{00}{00}}} \ \underline{\hspace{0.5in}} \ \boxed{\phantom{\frac{00}{00}}} \ \boxed{\phantom{\frac{00}{00}}} \ \boxed{\phantom{\frac{00}{00}}}\)
Now include the digit 1 to make two different four-digit numbers. Compare the numbers.
\(\boxed{\phantom{\frac{00}{00}}} _{\ \huge{,}} \ \boxed{\phantom{\frac{00}{00}}} \ \boxed{\phantom{\frac{00}{00}}} \ \boxed{\phantom{\frac{00}{00}}} \ \underline{\hspace{0.5in}} \ \boxed{\phantom{\frac{00}{00}}} _{\ \huge{,}} \ \boxed{\phantom{\frac{00}{00}}} \ \boxed{\phantom{\frac{00}{00}}} \ \boxed{\phantom{\frac{00}{00}}}\)
Shuffle the cards. Repeat what you did earlier with new cards.
Four-digit numbers
\(\boxed{\phantom{\frac{00}{00}}} _{\ \huge{,}} \ \boxed{\phantom{\frac{00}{00}}} \ \boxed{\phantom{\frac{00}{00}}} \ \boxed{\phantom{\frac{00}{00}}} \ \underline{\hspace{0.5in}} \ \boxed{\phantom{\frac{00}{00}}} _{\ \huge{,}} \ \boxed{\phantom{\frac{00}{00}}} \ \boxed{\phantom{\frac{00}{00}}} \ \boxed{\phantom{\frac{00}{00}}}\)
Five-digit numbers
\(\boxed{\phantom{\frac{00}{00}}} \ \boxed{\phantom{\frac{00}{00}}} _{\ \huge{,}} \ \boxed{\phantom{\frac{00}{00}}} \ \boxed{\phantom{\frac{00}{00}}} \ \boxed{\phantom{\frac{00}{00}}} \ \underline{\hspace{0.5in}} \ \boxed{\phantom{\frac{00}{00}}} \ \boxed{\phantom{\frac{00}{00}}} _{\ \huge{,}}\ \boxed{\phantom{\frac{00}{00}}} \ \boxed{\phantom{\frac{00}{00}}} \ \boxed{\phantom{\frac{00}{00}}} \ \)
Six-digit numbers
\(\boxed{\phantom{\frac{00}{00}}} \ \boxed{\phantom{\frac{00}{00}}} \ \boxed{\phantom{\frac{00}{00}}} _{\ \huge{,}} \ \boxed{\phantom{\frac{00}{00}}} \ \boxed{\phantom{\frac{00}{00}}} \ \boxed{\phantom{\frac{00}{00}}} \ \underline{\hspace{0.5in}} \ \boxed{\phantom{\frac{00}{00}}} \ \boxed{\phantom{\frac{00}{00}}} \ \boxed{\phantom{\frac{00}{00}}} _{\ \huge{,}} \ \boxed{\phantom{\frac{00}{00}}} \ \boxed{\phantom{\frac{00}{00}}} \ \boxed{\phantom{\frac{00}{00}}} \)
For each pair you compared, how did you decide which number is greater?
Student Response
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Advancing Student Thinking
When answering the question about how they compared the numbers, students may say that they “just know” which one was greater. Encourage them to think about the features of the numbers that gave them an immediate clue about the size of the numbers, or the features that they didn’t find as useful.
Activity Synthesis
Select students to display their number statements and read them. Ask if the class agrees with their comparison.
“How did you decide which number is greater? Did you compare every digit?”
Select students who wrote numbers with the same first digit (or the same first two digits) to share their number statements. Ask them to explain how they compared the numbers.
If no students mentioned that the digits in some places matter more than those in others, ask them about it.
“Did you pay attention only to some digits but not others?”
“Which ones did you prioritize? Were there any you tended to ignore?”


aligns: no