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: 
Construct a tangent line from a point outside a given circle to the circle.

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: 
No. This task does not involve drawing lines that are tangent to circles. The only line that may be drawn is the ray between points P and B.

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_neg_0

HS_2
standard_description: Derive the equation of a parabola given a focus and directrix.
problem_activity: Narrative
The purpose of this activity is for students to learn stage 3 of the Picture Books center. Students look through picture books and notice and describe shapes they see in the pictures.
Required Materials
Materials to Gather
Picture books
Materials to Copy
Picture Books Stage 3 Recording Sheet
Required Preparation
Each group of 2
–
4 needs at least one picture book that shows a variety of shapes throughout the book.
Launch
Groups of 2
Give each student a recording sheet and each group 2
–
4 picture books.
“We are going to learn a new way to do the Picture Books center.”
“Your group will look through picture books and notice and describe shapes you see in the pictures. On your recording sheet, you will each sketch the shape you see, describe it, and name it.”
Activity
10 minutes: partner work time
Monitor for different shapes students notice.
Activity Synthesis
“What shapes did you find most often?”


aligns: no