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: 
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 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_pos_0

HS_2
standard_description: Use addition to find the total number of objects arranged in rectangular arrays with up to 5 rows and up to 5 columns; write an equation to express the total as a sum of equal addends.
problem_activity: Narrative
The purpose of this activity is for students to partition rectangles to create rows and columns of equal-size squares. In the launch, students build an array with tiles and then represent it on a rectangle with tick marks as guidance. They will partition rectangles without tick marks in the next activity.
MLR2 Collect and Display.
Synthesis: Direct attention to words collected and displayed from the previous lessons. Include the word “partition.” Invite students to borrow language from the display as needed, and update it throughout the lesson.
Advances: Conversing, Reading
Required Materials
Materials to Gather
Inch tiles
Rulers
Launch
Groups of 2
Give students rulers and inch tiles.
Activity
“Use 8 tiles to make a rectangle. Your tiles should be in 2 rows.”
1 minute: independent work time
“Now, draw lines in the rectangle to show the squares. It should have the same number of equal-size squares as the rectangle you made out of tiles. You may use a ruler if it helps you.”
1 minute: independent work time
“You will draw lines to partition 2 more rectangles into equal-size squares. You can also use the tiles to build it first, if that helps.”
10 minutes: independent work time
Student Facing
Build a rectangle with 8 tiles arranged in 2 rows. Use a ruler to partition the rectangle to match the rectangle you made.
[IMG]
Use a ruler to partition the rectangle using the tick marks as a guide.
[IMG]
How many rows of equal-size squares did you make?
How many columns did you make?
Write 2 equations to represent the total number of equal-size squares.
Use a ruler to partition the rectangle using the tick marks as a guide.
[IMG]
How many rows of equal-size squares did you make?
How many columns did you make?
Write 2 equations to represent the total number of equal-size squares.
Student Response
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Advancing Student Thinking
If students create equations that match the total number of squares, but do not represent the sum of squares in each row or the sum of squares in each column, consider asking:
“How does your equation match the array?”
“Can you write an equation with equal addends that shows the sum of each row or column?”
Activity Synthesis
Invite 1
–
2 students to share their rectangles and equations for their rectangle with 3 rows and 5 columns. (
\(3 + 3 + 3 + 3 + 3 = 15\)
or
\(5 + 5 + 5 = 15\)
)
Draw a rectangle and partition to show:
[IMG]
“How is this partition different from what we did in this activity?” (The squares aren’t the same size and the last column has 4 not 3.)


aligns: yes