In this activity, students sort and compare the attributes of triangles, quadrilaterals, pentagons, and hexagons. They use informal vocabulary as they describe the defining and nondefining attributes of shapes. As an informal assessment, listen as students describe how they sort and categorize the shapes within each group (MP6).

Although students may know some shape names, they may sort their shapes by any attribute during the first sort. In the Activity Synthesis, all students sort the shapes, based on the numbers of sides and corners. In the next activity, students will match shape names to the groups that are sorted based on the numbers of sides and corners..

This activity uses MLR2 Collect and Display. Advances: conversing, reading, writing

• “Can you explain how you decided where to put each shape?”
• “What could you name each of your categories?”

• Display the recorded words and phrases.
• As needed, ask students to clarify the meaning of words and phrases, with examples from the cards.
• Invite previously selected groups to share how they sorted based on the number of sides of each shape.
• “Now work with your partner to sort your own shapes into categories, based on the number of sides of each shape.”
• As needed: “If your shapes are already sorted based on the number of sides of each shape, talk with your partner about other names you know for the shapes in each of your categories.”
• 1 minute: partner work time
• “Now, work with your partner to sort your shapes, based on the number of corners of each shape.”
• 1 minute: partner work time
• “What did you notice when you sorted the shapes by the number of corners?” (We didn’t have to do anything. The same shapes are in each group.)

The purpose of this activity is for students to recognize shapes as triangles, quadrilaterals, pentagons, and hexagons, based on the numbers of sides and corners. Students gather clues about the defining attributes of each category by asking whether or not a shape belongs (“Is Shape X a _____?”). After each group has had the opportunity to ask a question, students gather additional clues or attempt to confirm their understanding of a category by making statements, using the frame “Shape X is a _____ because it has _____.” In the Activity Synthesis, students define the terms, based on the shared attributes of each category of shapes.

Representation: Develop Language and Symbols. Synthesis: Maintain a chart to record new vocabulary. Invite students to suggest words, attributes, or pictures that will help them remember the different shapes.
Supports accessibility for: Memory, Attention

• “Work with your partner to describe the four categories of shapes: triangles, quadrilaterals, pentagons, and hexagons.” (A triangle is a shape with 3 sides and 3 corners. A quadrilateral is a shape with 4 straight sides and 4 corners. A pentagon is a shape with 5 straight sides and 5 corners. A hexagon is a shape with 6 straight sides and 6 corners.)  
• Share and record responses.
• Display the shapes from the last question.
• “Would these shapes belong to any of these categories? Explain.” (A does not belong because it has 5 sides and 4 corners. B does not belong because it has 5 corners and 6 sides. C does not belong because it has 5 corners, 4 straight sides, and one curved side.)

If students describe their shape in a way that is not clear to their partner, consider asking:

• “What are some vocabulary words you've learned to describe shapes?”
• “How can you describe your shape, using some of these terms to help your partner name it?”

• “What clues did your partner give you that made it easy to guess their shape?” (number of sides, number of corners)
• “Were there any clues that did not help you guess the name of the shape?” (color, size)