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: 
Solve quadratic equations in one variable.

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


Answer: 
Yes. This task shows one quadratic equation with 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_pos_0

HS_1

im_task_001160_neg_0

HS_2
standard_description: Convert among different-sized standard measurement units within a given measurement system (e.g., convert 5 cm to 0.05 m), and use these conversions in solving multi-step, real world problems.
problem_activity: Activity
The purpose of this activity is to give students an opportunity to practice checking whether a particular value is a solution to an equation, and to recall properties of operations and equality that preserve the solution set of an equation.
This will be useful when students consider when and why equations have the same solution in the associated Algebra 1 lesson.
Monitor for students who:
check the value of
\(x\)
in only one expression and reason about the second expression
identify properties by name such as commutative, distributive, and associative
identify properties informally such as “changing the order doesn’t matter” or “you can add first and then multiply or multiply first and then add” or “you can multiply three or more terms in any order” or “you can add the same thing to each side”
manipulate the expressions
graph one or both expressions
Making graphing technology available gives students an opportunity to choose appropriate tools strategically.
Student Facing
For each pair of equations, decide whether the given value of
\(x\)
is a solution to one or both equations:
Is
\(x = 2\)
a solution to:
\(x(2 + 3) = 10\)
\(2x + 3x = 10\)
Is
\(x = 3\)
a solution to:
\(x - 4 = 1\)
\(4 - x = 1\)
Is
\(x = \text{-}2\)
a solution to:
\(7x = \text{-}14\)
\(x \boldcdot 14 = \text{-}28\)
Is
\(x = \text{-}1\)
a solution to:
\(x + 3 = 2\)
\(3 + x = 2\)
Is
\(x = \text{-5}\)
a solution to:
\(3 - x = 8\)
\(5 - x = 10\)
Is
\(x = (8 + 1)+3\)
a solution to:
\(\frac{12}{2} = \frac12(x)\)
\(18 = 2x\)
Is
\(x = 2\)
a solution to:
\(\frac{12}{x} = 6\)
\(6x = 12\)
Is
\(x = \frac{10}{3}\)
a solution to:
\(\text{-}1 + 3x = 9\)
\(9 = 3x - 1\)
Is
\(x = \frac12\)
a solution to:
\(5(x + 1) = \frac{15}{2}\)
\(5x + 1 = \frac{15}{2}\)
Student Response
Teachers with a valid work email address can
click here to register or sign in
for free access to Student Response.
Activity Synthesis
Ask students to talk to their neighbor about some things they can look for, to see if two equations are likely to have the same solution or different solutions. If needed, draw students’ attention to which equations had the same solution and which had different solutions, perhaps by displaying them for all to see, grouped by whether the equations were equivalent or not.
Call on students to share their thinking and make an informal list displayed for all to see. It’s fine if students do not name all possible properties, or only describe them informally. They will have more opportunities to encounter them formally in their Algebra 1 course.
Remind students that
equivalent
equations have the same solution set. Use the language of
equivalent
interchangeably with “have the same solution,” and monitor for students to pick up on this vocabulary.


aligns: no