few_shots: 
Example 1:
Concept/skill: 
Prove the addition and subtraction formulas for sine, cosine, and tangent and use them to solve problems.

Problem/activity:
Find the general solution for:
$${\mathrm{cos}\left({\pi\over2}+x\right)=\mathrm{tan}{\pi\over4}}$$


Answer: 
Yes. An initial step when solving for x in this problem requires the use of the addition formula for cosine on the left side of the equation.

Example 2:
Concept/skill: 
Understand that the graph of an equation in two variables is the set of all its solutions plotted in the coordinate plane, often forming a curve (which could be a line).

Problem/activity:
Task
Solve the quadratic equation
$$ x^2 = (2x - 9)^2 $$
using as many different methods as possible.


Answer: 
No. This task does not involve an equation in two variables. There is only one variable, x.

Example 3:
Concept/skill: 
Make formal geometric constructions with a variety of tools and methods (compass and straightedge, string, reflective devices, paper folding, dynamic geometric software, etc.). Copying a segment; copying an angle; bisecting a segment; bisecting an angle; constructing perpendicular lines, including the perpendicular bisector of a line segment; and constructing a line parallel to a given line through a point not on the line.

Problem/activity:
Task
Suppose $A$ is an angle with vertex $P$, as pictured below:
[IMG]
Draw a circle with center $P$ and with  radius $r \gt 0$.  Explain why the circle
meets each ray of angle $A$ in a single point.  Label these points $Q$ and $R$ respectively.
Draw circles with centers $Q$ and $R$ respectively and radius $r$.  These circles meet at $P$ and a second point to be labelled $B$.
Show that ray $\overrightarrow{PB}$  bisects angle $P$.


Answer: 
Yes. This task asks students to draw a ray that bisects an angle. The act of drawing circles and rays may involve compass and straightedge or dynamic geometric software.

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_001894_pos_0

HS_0

im_task_000870_neg_0

HS_1

im_task_001160_pos_0

HS_2
standard_description: Add up to four two-digit numbers using strategies based on place value and properties of operations.
problem_activity: Narrative
The purpose of this activity is for students to learn stage 5 of the Target Numbers center. Students subtract two-digit numbers to get as close to 0 as possible. For the introduction of this stage, invite students to count by 10 to 100 and represent their count with base-ten blocks. Then, they take turns rolling the 3 cubes to get a number to subtract. They choose one of the numbers on the cubes to represent the tens and a different number to represent the ones. Students subtract their tens and ones from the starting number. The difference becomes the first number in the next equation. The player who gets closest to 0 in 6 rounds, without going below 0, is the winner.
Required Materials
Materials to Gather
Base-ten blocks
Number cubes
Materials to Copy
Target Numbers Stage 5 Recording Sheet
Required Preparation
Each group of 2 students will need 3 number cubes.
Each group of 2 students will need base-ten blocks to represent at least 20 tens and 18 ones
.
Launch
Groups of 2
Give each student a copy of the recording sheet.
Give each group 3 number cubes and access to base-ten blocks.
“We are going to learn a new way to play Target Numbers. You and your partner will start with 100 and race to see who can reach a number less than 10 first.”
“Instead of using cards to decide whether to take away tens or ones, you will use number cubes to create a two-digit number and then subtract that number.”
“First, represent 100 with base-ten blocks."
As needed, invite students to count by 10 to 100 using the base-ten blocks or invite student to share how they might represent 100 with the blocks.
"When it’s your turn, roll all 3 number cubes. Pick 1 number to represent the tens and one number to represent the ones. Then show the subtraction with your blocks and write an equation on your recording sheet.”
“Take turns rolling and subtracting until the first person reaches a number less than 10.”
As needed, demonstrate a round with a student volunteer.
Activity
10
–
15 minutes: partner work
Activity Synthesis
Display equation:
\(73 - \underline{\hspace{1 cm}} = \underline{\hspace{1 cm}}\)
Draw or display number cubes showing 4, 2, and 5.
“What two-digit numbers could you create with this roll that would make you need to decompose a ten to subtract? How do you know?” (Sample response: 24 because if you subtract by place, there are only 3 ones, so you would need to decompose to take away 4 ones.)
“What two-digit numbers could you create that wouldn’t require decomposing a ten? How do you know?” (Sample response: 52 because if you subtract by place there are 3 ones and you can take away 2 ones from 3 ones.)
“What number would you create to try to get below 10 the fastest? Explain. (54 because it’s the number that lets you take away the most tens and ones.)


aligns: no