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


Concept/skill: 
Understand that by similarity, side ratios in right triangles are properties of the angles in the triangle, leading to definitions of trigonometric ratios for acute angles.

Answer: 
No. This problem does not directly teach how side ratios in right triangles lead to definitions of trigonometric ratios. Instead, it involves solving a trigonometric function.

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: 
Make formal geometric constructions with a variety of tools and methods (compass and straightedge, string, reflective devices, paper folding, dynamic geometric software, etc.). Copying a segment; copying an angle; bisecting a segment; bisecting an angle; constructing perpendicular lines, including the perpendicular bisector of a line segment; and constructing a line parallel to a given line through a point not on the line.

Answer: 
Yes. This task asks students to draw a ray that bisects an angle. The act of drawing circles and rays may involve compass and straightedge or dynamic geometric software.

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

shot_info: fl_problem_001894_neg_0

HS_0

im_task_000870_neg_0

HS_1

im_task_001160_pos_0

HS_2
standard_description: Understand that positive and negative numbers are used together to describe quantities having opposite directions or values (e.g., temperature above/below zero, elevation above/below sea level, credits/debits, positive/negative electric charge); use positive and negative numbers to represent quantities in real-world contexts, explaining the meaning of 0 in each situation.
problem_activity: Activity
In this activity, students find intercepts and slopes for pairs of equations. They should notice that the equations in each pair are multiples of one another and therefore are equivalent equations. Students look for and make use of structure (MP7) when they notice the relationships between the pairs of equations.
Launch
Ask students what they remember about
\(x\)
- and
\(y\)
-intercepts. One useful thing to remember is that the
\(x\)
-intercept of a graph occurs where the
\(y\)
-coordinate is zero. (Demonstrate using a graph, if needed.) So, to find the
\(x\)
-intercept of a graph representing an equation, you can replace
\(y\)
with 0 and solve the equation for
\(x\)
. (And vice versa to find the
\(y\)
-intercept.)
Ask students how they can use two points like
\((1,0)\)
and
\((0,8)\)
to find the slope of a line. (Using a formula like
\(m = \frac{y_2 - y_1}{x_2 - x_1}\)
, or a less-formal version like “subtract the y’s, subtract the x’s, then divide.
”
For this example the slope is -8 since
\(\frac{8 - 0}{0-1} = \text{-}8\)
.)
Student Facing
Here are some equations in pairs. For each equation:
Find the
\(x\)
-intercept and
\(y\)
-intercept of a graph of the equation.
Find the slope of a graph of the equation.
\(x + y = 6\)
and
\(2x + 2y = 12\)
\(3y - 15x = \text{-}33\)
and
\(y - 5x = \text{-}11\)
\(5x + 20y = 100\)
and
\(4x + 16y = 80\)
\(3x - 2y = 10\)
and
\(4y - 6x = \text{-}20\)
What do you notice about the pairs of equations?
Choose one pair of equations and rewrite them into slope-intercept form (
\(y = mx + b\)
). What do you notice about the equations in this form?
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
The purpose of the discussion is to show that equations that are multiples of one another will have graphs with the same intercepts and slope. Select students to share their solutions and methods for finding the intercepts and slope as well as things they notice. While students may notice many things, ensure it is mentioned that in each pair of equations, one is a multiple of the other.
Some questions for discussion:
"How would the graphs of each pair of equations look?" (Each graph would look like a single line since the two equations are equivalent. Time permitting, demonstrate this using graphing technology.)
"Select a pair of equations. Find another equation whose graph would have the same slope and intercepts as the pair already given." (Another multiple of either equation will work.)


aligns: no