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: Explain why a fraction a/b is equivalent to a fraction (n × a)/(n × b) by using visual fraction models, with attention to how the number and size of the parts differ even though the two fractions themselves are the same size. Use this principle to recognize and generate equivalent fractions.
Grade 4 expectations in this domain are limited to fractions with denominators 2, 3, 4, 5, 6, 8, 10, 12, and 100.
problem_activity: Narrative
The purpose of this activity is for students to reason about adding fractions with unlike denominators to add two equations to a partially-completed True or False activity. If there is time, students can facilitate their True or False with another group.
Launch
Groups of 2 or 4
“Now you will work with your group to complete a True or False activity. This activity has two equations missing. Decide on equations that would complete the True or False and write them on the blank lines.”
Activity
10 minutes: small-group work time
As students work, monitor for groups who discuss and design equations based on some of the following:
They create equations where the fractions on one side of the equation have unlike denominators and the other side consists of fractions with like denominators.
They create an equation where the common denominator is appropriate, but the corresponding fraction used is not equivalent.
They create an equation that is similar to a previous equation.
They create an equation where a similar strategy can be used to determine if it’s true.
Student Facing
Write two equations to complete the True or False task. Be prepared to share your reasoning for the equations.
\(\frac{8}{14}+\frac{3}{7}=\frac{4}{7}+\frac{3}{7}\)
_______________________
_______________________
Student Response
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Activity Synthesis
Choose small groups to share that had different reasons for their equations.
Ask students to share their completed True or False and ask the class to share reasons for the equations.
As each group shares, continually ask others in the class if they agree or disagree and the reasons why.


aligns: no