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

• “What makes the triangles different from 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 a dot grid to draw triangles and shapes that are not triangles. Students may use the shape cards to visualize and draw shapes.

The dot grid is included in the student book. A blackline master is also attached if more dot paper is needed.

• “Who thinks they have drawn a triangle that no one else has drawn?”
• 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 counting, adding and subtracting, or working with shapes. Students choose from previously introduced stages of these centers:

• Geoblocks
• How Are They the Same?
• Compare
• Counting Collections

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