Unit 7

Points, Lines, Rays, and Segments

Lesson 2

Angles and Angle Measurement

Expressions and Equations

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Let’s draw points, lines, line segments, and rays.

Unit 7 ● Lesson 2

Learning

Goal

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Finding Differences

Unit 7 ● Lesson 2 ● Warm-up

Find the value of each expression mentally.

• 90 – 45
• 270 – 45
• 270 – 135
• 360 – 135

What do these expressions have in common?

How did this observation—that the first numbers are all multiples of 90—help you find the value of the differences?

Number Talk

Slides are CC BY NC Kendall Hunt Publishing. Curriculum excerpts are CC BY Illustrative Mathematics.

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Card Sort: Who Am I?

Unit 7 ● Lesson 2 ● Activity 1

We used many different words to describe figures. We learned how to identify points, lines, and line segments.

Let’s act out each term with arms and hands.

We are going to continue to define points, lines, and line segments in this next activity. You are also going to use the cards to define another figure, a ray.

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Launch

Slides are CC BY NC Kendall Hunt Publishing. Curriculum excerpts are CC BY Illustrative Mathematics.

Card Sort: Who Am I?

Unit 7 ● Lesson 2 ● Activity 1

Your teacher will give you a set of cards that describe or illustrate points, lines, rays, and line segments.

Sort the cards into 4 groups. Each group should represent the attributes or characteristics of one of the geometric figures.

Pause for directions from your teacher before completing the graphic organizer.

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Slides are CC BY NC Kendall Hunt Publishing. Curriculum excerpts are CC BY Illustrative Mathematics.

Card Sort: Who Am I?

Unit 7 ● Lesson 2 ● Activity 1

• Which cards did you spend the most time debating as a group?
• A point might be tricky to think about. It is often represented by a dot or a circle, which could be large or small. But the point itself cannot be large or small since it only marks a location.
• What about a line? Why can it not be measured?
• Why is a ray also impossible to measure?

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Activity Synthesis

Slides are CC BY NC Kendall Hunt Publishing. Curriculum excerpts are CC BY Illustrative Mathematics.

Make Some Shapes

Unit 7 ● Lesson 2 ● Activity 2

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1. Each dot on the grid represents a point. Draw line segments to create:

a triangle a trapezoid a pentagon

a rhombus a hexagon a rectangle

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Slides are CC BY NC Kendall Hunt Publishing. Curriculum excerpts are CC BY Illustrative Mathematics.

Make Some Shapes

Unit 7 ● Lesson 2 ● Activity 2

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• Draw a combination of rays and line segments to create:

an uppercase letter a number a lowercase letter

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Slides are CC BY NC Kendall Hunt Publishing. Curriculum excerpts are CC BY Illustrative Mathematics.

Make Some Shapes

Unit 7 ● Lesson 2 ● Activity 2

• How many possible triangles can we draw on the dot paper? How many possible trapezoids? Hexagons?
• Did anyone not start or end their line segments or rays on a dot? Do the results still count as segments or rays?
• How did you distinguish line segments and rays when drawing numbers and letters in the second question?

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Activity Synthesis

Slides are CC BY NC Kendall Hunt Publishing. Curriculum excerpts are CC BY Illustrative Mathematics.

Points, Lines, Rays, and Segments

Unit 7 ● Lesson 2

Today we learned the meanings of points, lines, line segments, and rays, and we used those geometric parts to create drawings.

• How might we explain to a new student how lines, rays, and line segments are different?
• Are the dots on the paper we used today the only points that could be in the shapes and figures?
• The tip of the letter A and the ends of the horizontal segment don’t have any dots. Can we call these parts of the ‘A’ line segments?
• Is the bottom left corner of the letter L a point? Why or why not?

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Lesson Synthesis

Slides are CC BY NC Kendall Hunt Publishing. Curriculum excerpts are CC BY Illustrative Mathematics.

True or False: What’s the Point?

Unit 7 ● Lesson 2

Decide if each statement is true or false. If it is false, correct it.

1. A point marks a place.
2. This is a drawing of a ray.

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Cool-down

Slides are CC BY NC Kendall Hunt Publishing. Curriculum excerpts are CC BY Illustrative Mathematics.

True or False: What’s the Point?

Unit 7 ● Lesson 2

• A line can be curved or straight.
• This is a drawing of a segment.

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• The length of a ray can be measured.

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Cool-down

Slides are CC BY NC Kendall Hunt Publishing. Curriculum excerpts are CC BY Illustrative Mathematics.

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Slides are CC BY NC Kendall Hunt Publishing. Curriculum excerpts are CC BY Illustrative Mathematics.