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: Identify arithmetic patterns (including patterns in the addition table or multiplication table), and explain them using properties of operations. For example, observe that 4 times a number is always even, and explain why 4 times a number can be decomposed into two equal addends.
problem_activity: Narrative
The purpose of this activity is for students to describe patterns in the sequence of even and odd numbers when they count by 1. Students notice that even numbers are numbers that you count when you skip-count by 2 (MP7).
In order for all students to visualize the sequence, perform the activity where the whole class can be arranged in a circle with space for students to sit and stand. Depending on class size, the count may go beyond 20. It is ok for students to notice and wonder about even and odd numbers beyond 20, but maintain the focus throughout the lesson on numbers within 20.
Launch
Form the class into a circle with all students standing.
“We are going to count together by 1. The first person to count will say 0 and stay standing.”
“The next person will say their number and sit down. The next person will say their number and stay standing.”
“We will keep counting until everyone has said a number.”
As needed, demonstrate the stand-sit-stand-sit sequence.
Record the count:
[IMG]
Prompt students who are standing to say their numbers. (0, 2, 4, …)
Prompt students who are sitting to say their numbers. (1, 3, 5, …)
Activity
“Write down what you notice and what you wonder about the numbers in our count.”
3 minutes: independent work time
2 minutes: partner discussion
Monitor for students' responses that focus on even and odd number patterns to share in synthesis.
Student Facing
What did you notice? What do you wonder?
Student Response
Teachers with a valid work email address can
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Activity Synthesis
Share and record student responses.
Display:
[IMG]
“This is a list of all the even and odd numbers from 0 to 20.”
“What patterns do you notice?” (All the even numbers are numbers you say when you skip-count by 2. The digits 0, 2, 4, 6, 8 repeat in the ones place for even numbers. The digits 1, 3, 5, 7, 9 repeat in the ones place in odd numbers.)
“How could you use these patterns to tell if a number of objects is even or odd?” (If the number is an even number you say it when you skip-count by 2.)


aligns: no