Lesson 5
Some Triangles, All Triangles
Warmup: Which One Doesn’t Belong: Shapes (10 minutes)
Narrative
Launch
 Groups of 2
 Display the image.
 “Pick one that doesn’t belong. Be ready to share why it doesn’t belong.”
 1 minute: quiet think time
Activity
 “Discuss your thinking with your partner.”
 2–3 minutes: partner discussion
 Share and record responses.
Student Facing
Which one doesn’t belong?
Student Response
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Activity Synthesis
 “Let’s find at least one reason why each one doesn’t belong.”
Activity 1: Triangles and “Not Triangles” (10 minutes)
Narrative
The purpose of this activity is for students to analyze examples and nonexamples of triangles. As students compare examples and nonexamples, they identify and articulate the defining attributes of triangles (MP6).
Advances: Speaking, Conversing
Supports accessibility for: Conceptual Understanding, VisualSpatial Processing
Required Materials
Materials to Gather
Required Preparation
 Each group of 2 needs a set of Flat Shape Cards from a previous lesson.
Launch
 Groups of 2
 Display the first question.
 “Here are four triangles. What do all of these triangles have in common?” (They all have three sides and three corners. They are all pointy. They are all closed.)
 30 seconds: quiet think time
 “Share your thinking with your partner.”
 2 minutes: partner discussion
 Share responses.
 If a student shares that all the triangles are white, ask, “If I colored one of these shapes in red, would it still be a triangle?”
Activity
 Read the second question.
 “Work with your partner to think of what makes these ‘not triangles’ different from the triangles in the first problem.”
 3 minutes: partner discussion
Student Facing
 These are triangles.
What is the same about all these triangles?
 These are not triangles.
What makes these shapes different from the triangles?
Student Response
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Activity Synthesis
 “What makes the triangles different than the 'not triangles'?”
 Give each group a set of shape cards from previous lessons.
 “Work with your partner to sort your shape cards into the categories of ‘triangles’ and ‘not triangles.’”
 Share responses.
Activity 2: Draw Triangles (10 minutes)
Narrative
Required Materials
Materials to Gather
Materials to Copy
 Centimeter Dot Paper  Standard
Required Preparation
 Each group needs a set of Flat Shape Cards from the previous activity.
Launch
 Groups of 2
 Give each group a set of flat shape cards and two pieces of dot paper.
 “Choose three dots. Connect the dots.”
 30 seconds: independent work time
 “Compare your drawing with your partner. What do you notice?” (We both drew triangles. The triangles are different sizes. They both have three sides.)
 1 minute: partner share
 Share responses.
Activity
 “Use the dot paper in your book to draw three triangles and three shapes that are not triangles. You may use the shape cards to help you.”
 6 minutes: independent work time

Monitor for some triangles and 'not triangles' to share during the lesson synthesis.
Student Facing

Draw 3 different triangles.

Draw 3 different shapes that are not triangles.
Student Response
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Activity Synthesis
 “Who thinks they drew a triangle that no one else drew?”
 Invite students to share their shapes and explain how they know they are triangles.
Activity 3: Centers: Choice Time (20 minutes)
Narrative
The purpose of this activity is for students to choose from activities that offer practice adding and subtracting or working with shapes. Students choose from any stage of previously introduced centers.
 Geoblocks
 How Are They the Same
 Compare
 How Close
Required Materials
Materials to Gather
Required Preparation
Gather materials from previous centers:
 Geoblocks, Stage 3
 How Are They the Same?, Stage 1
 Compare, Stage 1
 How Close, Stages 13
Launch
 Groups of 2
 “Now you are going to choose from centers we have already learned.”
 Display the center choices in the student book.
 “Think about what you would like to do first.”
 30 seconds: quiet think time
Activity
 Invite students to work at the center of their choice.
 8 minutes: center work time
 “Choose what you would like to do next.”
 8 minutes: center work time
Student Facing
Choose a center.
Geoblocks
How Are They the Same?
Compare
How Close?
Activity Synthesis
 “How did you decide which centers to choose today?”
Lesson Synthesis
Lesson Synthesis
“Today we looked at shapes that are triangles and shapes that are not triangles. Then we drew our own shapes.”
Display shapes drawn in a previous activity. “How can we tell if these shapes are triangles or not?” (If they are triangles they will have three sides, three corners, the sides will be straight and the shapes will be closed.)
Cooldown: Unit 7, Section A Checkpoint (0 minutes)
CoolDown
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