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, assess whether the following problem or activity is 'aligned' with the given Common Core standard in Mathematics.

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: Tell and write time from analog and digital clocks to the nearest five minutes, using a.m. and p.m.
problem_activity: Narrative
The purpose of this activity is to analyze a clock showing a time when it can be difficult to tell the difference between the hour and the minute hand. This activity allows students to discuss how they know where the hands are placed when the time is to the hour.
Launch
Groups of 2
Display the clock in the first problem.
“Diego and Priya read the clock and got two different times.”
“Who is correct? How do you know?”
Activity
2 minutes: partner discussion
5 minutes: independent work time
Monitor for a student who says the hour hand is pointing to 6 and one who says that for 12:30 the hour hand should be between 12 and 1.
Student Facing
[IMG]
Diego says this clock shows 6:00.
Priya says the clock shows 12:30.
Who do you agree with? Why?
Synthesis:
[IMG]
[IMG]
Student Response
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Activity Synthesis
Invite previously identified students to share.
“Why do you think Priya got mixed up? What could you say to help her revise her thinking?” (Priya mixed up the minute and hour hands. I could remind her that the short hand is the hour and the long hand is the minute. I could remind her that if it was 12:30 the hour hand would have to be between two numbers.)
“On the blank clock, draw hands to show 12:30.”


aligns: no