options: Operations & Algebra: students learn to solve problems using algebraic thinking and operations such as addition, subtraction, multiplication, and division. They may learn to identify and explain arithmetic patterns, evaluate or manipulate numerical expressions, and reason with equations and inequalities.

Number Systems and Quantity: students learn to understand the complex number system and reason quantitatively.

Geometry: students learn to classify geometric figures by their properties, and understand and compare the relationships between them. Students develop and use formulas to compute lengths, areas, and volumes, and they use transformations to generate new shapes and compare existing ones. Geometry can be studied with and without coordinates.

Ratios & Proportional Relationships: students learn to recognize, describe, represent, and reason with ratios, rates, proportional relationships, and percent.

Statistics & Probability: students learn to analyze and produce data distributions, and build understanding of univariate and bivariate data. They learn to interpret data, make statistical inferences, justify conclusions, understand rules of probability, and use probability to make decisions.

Measurement & Data: students learn to work with data and measure attributes such as time, money, length, area, and volume. They may learn to compare measurements to operations and convert between different units of measure.

Counting & Cardinality: students learn to know number names and the count sequence, count to tell the number of objects, and compare numbers.

Number & Operations in Base Ten: students learn to work with the base-ten system and build place value understanding.

Modeling: students learn to choose and use appropriate mathematics and statistics to analyze real-world empirical situations, improve decisions, and report on their conclusions and the reasoning behind them.

Number & Operations - Fractions: students learn to understand fractions as numbers and may work with them using addition, subtraction, multiplication, and division.

Functions: students learn to define, use, and evaluate functions to model relationships between quantities.
problem_activity: Activity
The goal of this activity is to practice applying the definition of rotation. In this activity, students rotate a segment around its endpoint to create an isosceles triangle. By rotating a segment around one endpoint, students can observe that the distance between the center of rotation and a point is the same as the distance between the center of rotation and the image of that point. This observation is later captured in the formal definition of rotation.
Making dynamic geometry software available gives students an opportunity to choose appropriate tools strategically (MP5).
Digital
Launch
Action and Expression: Internalize Executive Functions.
Chunk this task into more manageable parts to aide students who benefit from support with organizational skills in problem solving. For example, present one question at a time and ensure students complete each step correctly before moving on to the next step.
Supports accessibility for: Organization; Attention
Student Facing
Draw a segment. Label the endpoints
\(A\)
and
\(B\)
.
Rotate segment
\(AB\)
clockwise around center
\(B\)
by 90 degrees. Label the new endpoint
\(A’\)
.
Use the Polygon tool to draw triangle
\(ABA'\)
.
What kind of triangle did you draw? What other properties do you notice in the figure? Explain your reasoning.
Draw a segment. Label the endpoints
\(C\)
and
\(D\)
.
Rotate segment
\(CD\)
counterclockwise around center
\(D\)
by 30 degrees. Label the new endpoint
\(C’\)
.
Rotate segment
\(C’D\)
counterclockwise around center
\(D\)
by 30 degrees. Label the new endpoint
\(C’’\)
.
Use the Polygon tool to draw triangle
\(CDC’’\)
.
What kind of triangle did you draw? What other properties do you notice in the figure? Explain your reasoning.
Student Response
Teachers with a valid work email address can
click here to register or sign in
for free access to Student Response.
Student Facing
Are you ready for more?
You constructed an equilateral triangle by rotating a given segment around one of its endpoints by a specific angle measure. An equilateral triangle is an example of a
regular polygon
: a polygon with all sides congruent and all interior angles congruent. Try to construct some other regular polygons with this method.
Student Response
Teachers with a valid work email address can
click here to register or sign in
for free access to Extension Student Response.
Print
Launch
Briefly demonstrate how to create an angle of a given measure with a protractor and ask students to use their protractors along with you.
Making dynamic geometry software available gives students an opportunity to choose appropriate tools strategically (MP5). You may wish to demonstrate using GeoGebra Geometry in Math Tools.
Action and Expression: Internalize Executive Functions.
Chunk this task into more manageable parts to aide students who benefit from support with organizational skills in problem solving. For example, present one question at a time and ensure students complete each step correctly before moving on to the next step.
Supports accessibility for: Organization; Attention
Student Facing
Draw a segment. Label the endpoints
\(A\)
and
\(B\)
.
Rotate segment
\(AB\)
clockwise around center
\(B\)
by 90 degrees. Label the new endpoint
\(A’\)
.
Connect
\(A\)
to
\(A’\)
and lightly shade in the resulting triangle.
What kind of triangle did you draw? What other properties do you notice in the figure? Explain your reasoning.
Draw a segment. Label the endpoints
\(C\)
and
\(D\)
.
Rotate segment
\(CD\)
counterclockwise around center
\(D\)
by 30 degrees. Label the new endpoint
\(C’\)
.
Rotate segment
\(C’D\)
counterclockwise around center
\(D\)
by 30 degrees. Label the new endpoint
\(C’’\)
.
Connect
\(C\)
to
\(C’’\)
and lightly shade in the resulting triangle.
What kind of triangle did you draw? What other properties do you notice in the figure? Explain your reasoning.
Student Response
Teachers with a valid work email address can
click here to register or sign in
for free access to Student Response.
Student Facing
Are you ready for more?
You constructed an equilateral triangle by rotating a given segment around one of its endpoints by a specific angle measure. An equilateral triangle is an example of a
regular polygon
: a polygon with all sides congruent and all interior angles congruent. Try to construct some other regular polygons with this method.
Student Response
Teachers with a valid work email address can
click here to register or sign in
for free access to Extension Student Response.
Anticipated Misconceptions
Students may not notice any properties other than that rotation preserves distances to the center of rotation. Encourage these students to use tracing paper to make other conjectures about side lengths or angles.
Activity Synthesis
Display an isosceles triangle
\(ABC\)
with base
\(BC\)
.
Here are some key conjectures and observations students should come away from the discussion with:
Rotations preserve the distance to the center of rotation.
The angle bisector of angle
\(A\)
is also the perpendicular bisector of the base (
\(BC\)
) of an isosceles triangle.
The two base angles (angle
\(B\)
and angle
\(C\)
) of an isosceles triangle are congruent.
An isosceles triangle where angle
\(A\)
is 60 degrees is also equilateral.
It is not necessary at this time to formalize the language of these ideas. This will come later as students prove some of these statements in a subsequent unit.


correct_option_index: 2