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, determine whether the following problem or activity can enable students to understand the concepts or skills in the provided description.

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: Recognize and represent proportional relationships between quantities.
problem_activity: Activity
This activity continues work done in the previous lesson that connected various representations of proportional relationships including images, equations, and descriptions. In this activity students match diagrams, descriptions, and equations that represent a proportional relationship, involving variables
\(x\)
and
\(y\)
. Students then create their own diagram to represent an equation.
Identify students that create diagrams representing each of the unmatched equations, so they can share their work during the discussion.
Launch
Give students 7–10 minutes of quiet think time on the questions. Follow with whole-class discussion.
Representation: Internalize Comprehension.
Begin the activity with concrete or familiar contexts. For example, display a tape diagram with concrete values for
\(x\)
and
\(y\)
such as 20 and 15 respectively. Ask students “How much did 20 decrease by to get to 15?” Highlight the connections between the concrete and abstract tape diagrams. In the concrete tape diagram, 20 decreased by
\(\frac{1}{4}\)
to get 15. In the abstract tape diagram,
\(x\)
also decreased by
\(\frac{1}{4}\)
to get
\(y\)
.
Supports accessibility for: Conceptual processing; Memory
Student Facing
Match each diagram with a description and an equation.
Diagrams:
[IMG]
Descriptions:
An increase by
\(\frac14\)
An increase by
\(\frac13\)
An increase by
\(\frac23\)
A decrease by
\(\frac15\)
A decrease by
\(\frac14\)
Equations:
\(y=1.\overline{6}x\)
\(y=1.\overline{3}x\)
\(y=0.75x\)
\(y=0.4x\)
\(y=1.25x\)
Draw a diagram for one of the unmatched equations.
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 previously identified students to share their diagrams and explain how they represent the equation they chose. Then, ask students that did not share their diagrams to explain whether
\(x\)
(or
\(y\)
) is increased or decreased by some amount in the discussed equations.
Representing, Writing: MLR3 Clarify, Critique, Correct.
Present an incorrect diagram to represent one of the unused equations that reflects a possible misunderstanding from the class. For example, for the equation
\(y=0.75x\)
, draw a diagram where
\(y\)
is greater than
\(x\)
. Prompt students to identify the error, and then write a correct diagram to represent the equation. This will support students to understand the relationship between equations and diagrams.
Design Principle(s): Maximize meta-awareness


aligns: yes