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.

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.

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

Functions: students learn to define, use, and evaluate functions to model relationships between quantities.

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.

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

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

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.

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

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.

Number & Operations - Fractions: students learn to understand fractions as numbers and may work with them using addition, subtraction, multiplication, and division.
problem_activity: Narrative
This warm-up prompts students to visualize the idea of arranging angles around a point and adding their measurements as more pieces are added. The angles are familiar angles:
\(90^\circ\)
,
\(180^\circ\)
, and
\(270^\circ\)
. Students previously arrived at these benchmarks by decomposing a full turn or
\(360^\circ\)
. Here, they compose a full turn from
\(90^\circ\)
angles.
The work here familiarizes students with the context and mathematics that might be involved later in the lesson. In the subsequent activities, students will compose and decompose paper cutouts of angles to determine angle measurements.
Launch
Groups of 2
Display the image.
“What do you notice? What do you wonder?”
1 minute: quiet think time
Activity
“Discuss your thinking with your partner.”
1 minute: partner discussion
Share and record responses.
Student Facing
What do you notice? What do you wonder?
[IMG]
Student Response
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Activity Synthesis
“What angles do you think are the measurement of each angle?” (They look like
\(90^\circ\)
,
\(180^\circ\)
, and
\(270^\circ\)
angles.)
“How do you know?” (If the paper is a rectangle, then the corner pieces are right angles or
\(90^\circ\)
each. Two of the corner pieces would be
\(90+90\)
. Three pieces would be
\(90+ 90+90\)
.)
“What angle would we get if we add the last corner piece?” (
\(360^\circ\)
)


correct_option_index: 4