Lesson 5

This warm-up prompts students to compare four two-dimensional shapes. It gives students a reason to use language precisely (MP6). It gives the teacher an opportunity to hear how students use informal and formal language to talk about characteristics of the items in comparison to one another. During the synthesis, ask students to explain the meaning of any terminology they use, such as curved and open.

• 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

• “Discuss your thinking with your partner.”
• 2–3 minutes: partner discussion
• Share and record responses.

• “Let’s find at least one reason why each one doesn’t belong.”

The purpose of this activity is for students to analyze examples and non-examples of triangles. As students compare examples and non-examples, they identify and articulate the defining attributes of triangles (MP6).

• Each group of 2 needs a set of Flat Shape Cards from a previous lesson.

• 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?”

• 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

• “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.

The purpose of this activity is for students to draw triangles. Students use dot paper to draw triangles and then draw shapes that are not triangles. Students may use the shape cards to visualize and draw shapes.

• Each group needs a set of Flat Shape Cards from the previous activity.

• 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.

• “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.

• “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.

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

Gather materials from previous centers:

• Geoblocks, Stage 3
• How Are They the Same?, Stage 1
• Compare, Stage 1
• How Close, Stages 1-3

• 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

• 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

• “How did you decide which centers to choose today?”