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: Order three objects by length; compare the lengths of two objects indirectly by using a third object.
problem_activity: Narrative
The purpose of this activity is for students to order three objects by length. Students line up objects from shortest to longest and longest to shortest. Students need to attend to the language in the question to know which way to order the objects. The language and reasoning students use in this activity helps prepare them to compare the length of objects indirectly in future lessons.
Required Materials
Materials to Gather
Materials from a previous activity
Required Preparation
Each group of 4 needs the collection of objects from the previous activity.
Launch
Groups of 4
Give each group 10–12 objects.
Activity
Read the task statement.
5 minutes: small-group work
Monitor for students who line up the endpoints of the objects.
Student Facing
Pick 3 objects.
With your partner, put the objects in order from
shortest
to longest.
Trace or draw your objects.
Pick 3 new objects.
With your partner, put them in order from
longest to shortest
.
Write the names of the objects in order from longest to shortest.
Student Response
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Advancing Student Thinking
If students appear to order their objects correctly without lining them up, consider asking:
“How did you order your objects from ___ (shortest to longest or longest to shortest)?”
“How could you prove to someone that your objects are ordered correctly?”
Activity Synthesis
Invite previously identified students to demonstrate how they ordered three objects from shortest to longest.
Display the three objects with the endpoints lined up so all students can see.
“What statements can you make to compare the length of their objects?” (The ___ is longer than the ___ and ___.)
As time permits, repeat by inviting a previously identified students to demonstrate how they ordered three objects from longest to shortest.


aligns: yes