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


Mathematical concept/skill options: 
A. Prove and apply trigonometric identities.
B. Model periodic phenomena with trigonometric functions.
C. Interpret functions that arise in applications in terms of the context.
D. Build a function that models a relationship between two quantities.
E. Define, evaluate, and compare functions.
F. Use functions to model relationships between quantities.
G. Understand the concept of a function and use function notation.
H. Analyze functions using different representations.
I. Extend the domain of trigonometric functions using the unit circle.
J. Interpret expressions for functions in terms of the situation they model.
K. Build new functions from existing functions.
L. Construct and compare linear and exponential models and solve problems.


Thought: This problem applies trigonometric identities, including the angle addition formula for cosine.
Answer: A

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


Mathematical concept/skill options: 
A. Apply and extend previous understandings of arithmetic to algebraic expressions.
B. Write expressions in equivalent forms to solve problems.
C. Understand solving equations as a process of reasoning and explain the reasoning.
D. Use the four operations with whole numbers to solve problems.
E. Generate and analyze patterns.
F. Understand and apply properties of operations and the relationship between addition and subtraction.
G. Use properties of operations to generate equivalent expressions.
H. Solve real-life and mathematical problems using numerical and algebraic expressions and equations.
I. Represent and analyze quantitative relationships between dependent and independent variables.
J. Understand properties of multiplication and the relationship between multiplication and division.
K. Work with equal groups of objects to gain foundations for multiplication.
L. Represent and solve problems involving multiplication and division.
M. Solve problems involving the four operations, and identify and explain patterns in arithmetic.
N. Work with radicals and integer exponents.
O. Interpret the structure of expressions.
P. Solve equations and inequalities in one variable.
Q. Understand addition as putting together and adding to, and understand subtraction as taking apart and taking from.
R. Multiply and divide within 100.
S. Represent and solve problems involving addition and subtraction.
T. Use polynomial identities to solve problems.
U. Represent and solve equations and inequalities graphically.
V. Understand the connections between proportional relationships, lines, and linear equations.
W. Reason about and solve one-variable equations and inequalities.
X. Rewrite rational expressions.
Y. Understand the relationship between zeros and factors of polynomials.
Z. Perform arithmetic operations on polynomials.
AA. Create equations that describe numbers or relationships
AB. Analyze and solve linear equations and pairs of simultaneous linear equations.
AC. Gain familiarity with factors and multiples.
AD. Write and interpret numerical expressions.
AE. Add and subtract within 20.
AF. Work with addition and subtraction equations.
AG. Solve systems of equations.
AH. Analyze patterns and relationships.


Thought: This task asks students to solve an equation in one variable. Since the problem asks for many different solution methods, students are also encouraged to solve the problem graphically.
Answer: P, U

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 $P$.


Mathematical concept/skill options: 
A. Apply trigonometry to general triangles.
B. Understand similarity in terms of similarity transformations.
C. Analyze, compare, create, and compose shapes.
D. Prove geometric theorems.
E. Make geometric constructions.
F. Graph points on the coordinate plane to solve real-world and mathematical problems.
G. Understand congruence and similarity using physical models, transparencies, or geometry software.
H. Understand congruence in terms of rigid motions.
I. Draw, construct, and describe geometrical figures and describe the relationships between them.
J. Translate between the geometric description and the equation for a conic section.
K. Reason with shapes and their attributes.
L. Prove theorems involving similarity.
M. Explain volume formulas and use them to solve problems.
N. Find arc lengths and areas of sectors of circles.
O. Define trigonometric ratios and solve problems involving right triangles.
P. Use coordinates to prove simple geometric theorems algebraically.
Q. Visualize relationships between two-dimensional and three-dimensional objects.
R. Solve real-life and mathematical problems involving angle measure, area, surface area, and volume.
S. Understand and apply theorems about circles.
T. Identify and describe shapes (squares, circles, triangles, rectangles, hexagons, cubes, cones, cylinders, and spheres).
U. Solve real-world and mathematical problems involving volume of cylinders, cones, and spheres.
V. Classify two-dimensional figures into categories based on their properties.
W. Apply geometric concepts in modeling situations.
X. Solve real-world and mathematical problems involving area, surface area, and volume.
Y. Experiment with transformations in the plane.
Z. Understand and apply the Pythagorean Theorem.
AA. Draw and identify lines and angles, and classify shapes by properties of their lines and angles.


Thought: This task asks students to make geometric constructions, such as bisecting an angle.
Answer: E

Now, assign the following problem or activity to one or more relevant mathematical concepts/skills it teaches.
shot_info: fl_problem_001894

HS_0

im_task_000870

HS_1

im_task_001160

HS_2
options: Extend the domain of trigonometric functions using the unit circle.

Interpret expressions for functions in terms of the situation they model.

Build a function that models a relationship between two quantities.

Define, evaluate, and compare functions.

Build new functions from existing functions.

Use functions to model relationships between quantities.

Understand the concept of a function and use function notation.

Construct and compare linear and exponential models and solve problems.

Model periodic phenomena with trigonometric functions.

Analyze functions using different representations.

Prove and apply trigonometric identities.

Interpret functions that arise in applications in terms of the context.
problem_activity: Activity
The mathematical work in this activity centers on interpreting graphical and symbolic representations of a piecewise-defined function.
First, students interpret a graph of a piecewise function and make sense of the rules in terms of a situation. In particular, students consider the meaning of the open and solid circles on the graph and the input values that appear to "break" the graph.
Next, students interpret a couple of equations in cases notation that could define the function, making connections between the symbols and numbers in the notation and features of the graph.
Launch
Display the graph in the activity statement for all to see. Give students a minute to notice and wonder about something on or about the graph. Then, invite students to share what they noticed and wondered. If no students wondered whether the graph represents a function, ask students about it.
Arrange students in groups of 2. Give students a moment of quiet time to think about the first two questions, and then time to discuss their responses with their partner. Some students may not be familiar with the fact that mailing rates may depend on the weight of the items being mailed. Give students a brief introduction, as needed. Ask partners to pause for a whole-class discussion before continuing to the last question.
Ask students how they knew what to pay for mailing a letter that weighs 1 ounce, given that there are two output values that correspond to the input value of 1.
Students are likely to remember that open and closed circles are used to mark the boundary points of graphs of inequalities in one variable, and transfer that understanding to this graph. If not mentioned in students' explanations, clarify that:
An open circle at
\((0,0.5)\)
, for instance, means that, when 0 is the input, 0.5 is
not
the output.
A closed circle at
\((1, 0.5)\)
, for instance, means that, when 1 is the input, 0.5 is the output.
Next, ask students to analyze the two sets of rules in the last question.
Conversing: MLR2 Collect and Display.
As students work in small-groups, listen for and collect language and  gestures students use to describe a piecewise graph and equation. Capture the language that reflects the various ways students describe the notation in the equation, the visual appearance of the graph, the inequality sign, and open or closed circles. Write the students’ words on a visual display and update it throughout the remainder of the lesson. Remind students to borrow language from the display as needed. This will help students connect the notation with the features on the piecewise graph.
Design Principle(s): Maximize meta-awareness; Support sense-making
Student Facing
The relationship between the postage rate and the weight of a letter can be defined by a
piecewise function
.
The graph shows the 2018 postage rates for using regular service to mail a letter.
[IMG]
What is the price of a letter that has the following weight?
1 ounce
1.1 ounces
0.9 ounce
A letter costs $0.92 to mail. How much did the letter weigh?
Kiran and Mai wrote some rules to represent the postage function, but each of them made some errors.
\(\displaystyle K(w) = \begin{cases} 0.50, & 0\leq w\leq 1 \\ 0.71, & 1\leq w\leq 2 \\ 0.92, & 2\leq w\leq 3\\ 1.13, & 3\leq w\leq 3.5\\ \end{cases} \)
\(\displaystyle M(w) = \begin{cases} 0.50, & 0< w< 1 \\ 0.71, & 1< w< 2 \\ 0.92, & 2< w< 3\\ 1.13, & 3< w< 3.5\\ \end{cases}\)
Identify the error in each person’s work and write a corrected set of rules.
Student Response
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for free access to Student Response.
Student Facing
Are you ready for more?
Here is an image showing how the postal service specifies the different mailing rates.
Notice that it uses the language "weight not over (oz.)" to describe the different rates.
Explain or use a sketch to show how the graph would change if the postal service uses "under (oz.)" instead?
[IMG]
Student Response
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click here to register or sign in
for free access to Extension Student Response.
Activity Synthesis
Invite students to share their analyses of Mai and Kiran's work and identify the errors each person made. Highlight explanations that point out that:
In Kiran's rules, a letter that weighs 1, 2, or 3 ounces each has two possible rates. For example, for 1 ounce, it could be
$
0.50 or
$
0.71. For 2 ounces, it could be
$
0.71 or
$
0.92.
Mai's rules, on the other hand, excludes letters that weigh exactly 1, 2, or 3 ounces each. No rates are specified for those weights.
In both cases, the problem is with the inequality symbols used.
Discuss what the rules should be, making sure to connect the notation with the features on the graph. Ask students:
"How do we know whether to use
\(<\)
or
\(\le\)
by looking at the graph?" (A point with an open circle means the coordinate values of that point is not included, but values that are greater or are less, depending on the graph, are included. So an open circle corresponds to
\(<\)
or
\(>\)
. A point with a solid or closed circle means the coordinate values of that point are included, so it corresponds to
\(\le\)
or
\(\geq\)
.)
"By looking at the graph, how can you tell how many cases should be included in the equation?" (Each piece of the graph is a case.)
If time permits, ask students about the domain and range for this function. Assuming that mail item heavier than 3.5 ounces no longer qualifies as a letter, the domain would include weights that are greater than 0 but no more than 3.5 ounces (
\(0<x \le 3.5\)
). The corresponding range includes 0.50, 0.71, 0.92, 1.13, in dollars.
Representation: Develop Language and Symbols.
Create a display of important terms and vocabulary. Invite students to suggest language or diagrams to include that will support their understanding of: piecewise function, point with an open circle, point with a solid or closed circle.
Supports accessibility for: Conceptual processing; Language


correct_option_index: 9

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