few_shots: 
Example 1:
Problem/activity:
Find the general solution for:
$${\mathrm{cos}\left({\pi\over2}+x\right)=\mathrm{tan}{\pi\over4}}$$


Concept/skill: 
Prove the addition and subtraction formulas for sine, cosine, and tangent and use them to solve problems.

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:
Problem/activity:
Task
Solve the quadratic equation
$$ x^2 = (2x - 9)^2 $$
using as many different methods as possible.


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).

Answer: 
No. This task does not involve an equation in two variables. There is only one variable, x.

Example 3:
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 $P$.


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

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, does the problem or activity shown below enable students to learn the full intent of the following concept or skill?

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: Write and evaluate numerical expressions involving whole-number exponents.
problem_activity: Activity
In this activity, students get a chance to practice solving equations with a single variable. The equations resemble the types of equations students see in the associated Algebra 1 lesson after they substitute for a variable. Students will work in pairs and each partner is responsible for answering the questions in either column A or column B. Although each row has two different problems, they share the same answer. Ensure that students work their problems out independently and collaborate with one another when they do not arrive to the same answers. Students construct viable arguments and critique the reasoning of others (MP3) when they resolve errors by critiquing their partner's work or explaining their reasoning.
Launch
Arrange students in groups of 2.
Student Facing
Solve each equation.
{"table": [{"_attributes": {"border": "1"}, "thead": [{"tr": [{"th": [{"_attributes": {"scope": "row"}, "_value": "row"}, {"_attributes": {"scope": "col"}, "_value": "column A"}, {"_attributes": {"scope": "col"}, "_value": "column B"}]}]}], "tbody": [{"tr": [{"th": [{"_attributes": {"scope": "row"}, "_value": "1"}], "td": [{"p": [{"span": [{"_attributes": {"class": ["math", "math-repaired"], "data-png-file-id": "28834"}, "_value": "\\(4(2x+8)-10 = 14\\)"}]}]}, {"span": [{"_attributes": {"class": ["math", "math-repaired"], "data-png-file-id": "28861"}, "_value": "\\(4 + 2(\\text-3x+5)=20\\)"}]}]}, {"th": [{"_attributes": {"scope": "row"}, "_value": "2"}], "td": [{"p": [{"span": [{"_attributes": {"class": ["math", "math-repaired"], "data-png-file-id": "28897"}, "_value": "\\(3(x-4)+6 = 60\\)"}]}]}, {"span": [{"_attributes": {"class": ["math", "math-repaired"], "data-png-file-id": "28936"}, "_value": "\\(3(\\frac12x + 9)-5=55\\)"}]}]}, {"th": [{"_attributes": {"scope": "row"}, "_value": "3"}], "td": [{"p": [{"span": [{"_attributes": {"class": ["math", "math-repaired"], "data-png-file-id": "28976"}, "_value": "\\(4(\\frac{x+3}{2})-5 = 10\\)"}]}]}, {"span": [{"_attributes": {"class": ["math", "math-repaired"], "data-png-file-id": "29019"}, "_value": "\\(7-2(6x+1)=\\text-49\\)"}]}]}, {"th": [{"_attributes": {"scope": "row"}, "_value": "4"}], "td": [{"p": [{"span": [{"_attributes": {"class": ["math", "math-repaired"], "data-png-file-id": "29065"}, "_value": "\\(2x+(5-3x) = 14\\)"}]}]}, {"span": [{"_attributes": {"class": ["math", "math-repaired"], "data-png-file-id": "29114"}, "_value": "\\(1=5x+10-4x\\)"}]}]}, {"th": [{"_attributes": {"scope": "row"}, "_value": "5"}], "td": [{"p": [{"span": [{"_attributes": {"class": ["math", "math-repaired"], "data-png-file-id": "29167"}, "_value": "\\(4x + 2(3-x)=16\\)"}]}]}, {"span": [{"_attributes": {"class": ["math", "math-repaired"], "data-png-file-id": "29213"}, "_value": "\\(x+2(x-4)+5=12\\)"}]}]}, {"th": [{"_attributes": {"scope": "row"}, "_value": "6"}], "td": [{"p": [{"span": [{"_attributes": {"class": ["math", "math-repaired"], "data-png-file-id": "29263"}, "_value": "\\(2x - 2(3x-1) = 8\\)"}]}]}, {"span": [{"_attributes": {"class": ["math", "math-repaired"], "data-png-file-id": "29314"}, "_value": "\\(\\text-6x+2(4x+5)=7\\)"}]}]}]}]}]}
​​
Student Response
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Activity Synthesis
The purpose of the discussion is to recall strategies for solving equations with one variable. Select students to share their solutions including their reasoning for the steps they take.
Some questions for discussion:
"When there is a variable inside parentheses, how did you approach the problem?" (I distributed the value multiplying the parentheses to remove the parentheses then solved the equation as usual.)
"How could you check that your answer works using the original equation?" (I could substitute the value for
\(x\)
into the original equation and determine if the equation is true.)


aligns: no