options: Define trigonometric ratios and solve problems involving right triangles.

Understand and apply the Pythagorean Theorem.

Graph points on the coordinate plane to solve real-world and mathematical problems.

Identify and describe shapes (squares, circles, triangles, rectangles, hexagons, cubes, cones, cylinders, and spheres).

Prove theorems involving similarity.

Understand congruence in terms of rigid motions.

Understand similarity in terms of similarity transformations.

Draw, construct, and describe geometrical figures and describe the relationships between them.

Translate between the geometric description and the equation for a conic section.

Prove geometric theorems.

Draw and identify lines and angles, and classify shapes by properties of their lines and angles.

Solve real-world and mathematical problems involving area, surface area, and volume.

Use coordinates to prove simple geometric theorems algebraically.

Find arc lengths and areas of sectors of circles.

Reason with shapes and their attributes.

Classify two-dimensional figures into categories based on their properties.

Visualize relationships between two-dimensional and three-dimensional objects.

Analyze, compare, create, and compose shapes.

Make geometric constructions.

Understand congruence and similarity using physical models, transparencies, or geometry software.

Solve real-life and mathematical problems involving angle measure, area, surface area, and volume.

Explain volume formulas and use them to solve problems.

Solve real-world and mathematical problems involving volume of cylinders, cones, and spheres.

Experiment with transformations in the plane.

Apply geometric concepts in modeling situations.

Understand and apply theorems about circles.

Apply trigonometry to general triangles.
problem_activity: Activity
The purpose of this activity is to give students an opportunity to solve a relatively complicated application problem that requires an understanding of aspect ratio, the Pythagorean Theorem, and realizing that a good way to compare the sizes of two screens is to compare their areas. The previous activities in this lesson are meant to prepare students to understand the situation and suggest some strategies for tackling the problem.
Monitor for students using different approaches and strategies. Students may benefit from more time to think about this problem than is available during a typical class meeting.
Launch
Provide access to calculators that can take the square root of a number. The task statement is wordy, so consider using the Three Reads protocol to ensure students understand what the problem is saying and what it is asking.
We chose not to provide diagrams drawn to scale in the student materials, since it makes it somewhat obvious that the new phone design has a smaller screen area. However if desired, here is an image to show or provide to students:
[IMG]
Reading, Listening, Conversing: MLR6 Three Reads.
Use this routine to support reading comprehension of this word problem. Use the first read to orient students to the situation. Ask students to describe what the situation is about without using numbers (customers think that newly released smartphones have smaller screens). Use the second read to identify quantities and relationships. Ask students what can be counted or measured without focusing on the values (aspect ratios for phones manufactured before and after 2017). After the third read, invite students to brainstorm possible strategies they can use determine whether or not the new phones have a smaller screen, and by how much.
Design Principle(s): Support sense-making
Student Facing
Before 2017, a smart phone manufacturer’s phones had a diagonal length of 5.8 inches and an aspect ratio of
\(16:9\)
. In 2017, they released a new phone that also had a 5.8-inch diagonal length, but an aspect ratio of
\(18.5:9\)
. Some customers complained that the new phones had a smaller screen. Were they correct? If so, how much smaller was the new screen compared to the old screen?
Student Response
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Activity Synthesis
Invite students to share their ideas and progress with the class. If appropriate, students may benefit from an opportunity to clearly present their solution in writing.


correct_option_index: 1