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: Distinguish between defining attributes (e.g., triangles are closed and three-sided) versus non-defining attributes (e.g., color, orientation, overall size); build and draw shapes to possess defining attributes.
problem_activity: Narrative
The purpose of this activity is to introduce the language of
a half of
and
a fourth of
a
shape. Students begin by applying the language of halves and fourths, or quarters, to partition each shape. Students are asked to describe “how much” of each shape is shaded to elicit a variety of responses that include half, fourth, or quarter, including the phrases “of the square” or “of the circle.” Monitor for a variety of words and phrases to share in the synthesis including:
phrases that reference the pieces only (“one piece”).
phrases that reference that some, but not all of the shape is shaded (“part of it,” “a little bit”)
phrases that name the pieces (“a half,” “a fourth,” “a quarter”)
phrases that name the pieces in reference to the whole shape (“a half of the square,” “a fourth of the circle”)
All responses should be shared and compared in the synthesis to help build students understanding of the new vocabulary and the concept of fractional pieces of a whole (MP6).
Required Materials
Materials to Gather
Colored pencils or crayons
Launch
Groups of 2
Give students access to colored pencils or crayons.
Activity
Read the task statement.
2 minutes: independent work time.
2 minutes: partner discussion
Monitor for a range of ways to describe the amount shaded such as “some is shaded,” “one piece of the square is shaded,” “one out of two pieces is shaded,” or “a half is shaded.”
Student Facing
Split the square into halves.
[IMG]
Color in one of the halves.
How much of the square is colored in?
Split the circle into fourths.
[IMG]
Color in one of the fourths.
How much of the circle is colored in?
Student Response
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Activity Synthesis
Invite previously identified students to share for each problem. Sequence the students in the order described in the narrative.
“One piece of a shape split into two pieces that are the same size is called
a half
. One piece of a shape split into four pieces that are the same size is called
a fourth
.”
For each shape, invite students to describe how much is colored in. (A half of the square is colored in. A fourth of the circle is colored in.)


aligns: no