Lesson 1

The purpose of this warm-up is to elicit student ideas about examples and non-examples of triangles and how to describe the attributes of a category of shapes. This will be useful when students determine the defining attributes of quadrilaterals, pentagons, and hexagons in a later activity. While students may notice and wonder many things about these groups of shapes, how the shapes are alike and different are the important discussion points.

• Groups of 2
• Display the image.
• “What do you notice? What do you wonder?”
• 1 minute: quiet think time

• “Discuss your thinking with your partner.”
• 1 minute: partner discussion
• Share and record responses.

• Point to the group on the right.
• “Why do you think these shapes are together?” (They aren’t triangles. They have more than 3 sides. Some have curved lines.)
• “What could we name each group?” (triangles, not triangles)

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 non-defining 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 number of sides and corners. In the next activity, students will match shape names to the groups that are sorted based on number of sides and corners.

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

• Create a set of cards from the blackline master for each group of 2.
• Remove the shape name cards for this activity. Students will use them in the next activity.

• Groups of 2
• Give each group of 2 students a set of shape cards. 

• “In this activity, you will sort some cards into categories of your choosing. When you sort the shapes, you should work with your partner to come up with categories.”
• “Take a minute to look at the shapes and think about how you’ll sort them into categories.”
• 1 minute: quiet think time
• “Now, work with your partner to sort the shapes into categories in a way that makes sense to you.”
• 3–5 minutes: partner work time

MLR2 Collect and Display

• Circulate, listen for, and collect the language students use to describe the shapes and how they sort them into categories. Listen for: side, corner, square corner, triangle, hexagon, 3-sided, 4-sided, 5-sided, and 6-sided.
• Record students’ words and phrases on a visual display and update it throughout the lesson.
• If students sort shapes without discussing how they sort, consider asking:
  • “How did you sort these shapes?”
  • “What could you name each of your groups?”
• Monitor for students who explain how they sort the shapes by counting the number of sides on each shape.

If students sort the shapes without discussing how they sort, consider asking:

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

• 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 groups.”
• 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 number of sides and corners. Students gather clues about the defining attributes of each category by asking whether or not a shape belongs in the group (“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 synthesis, students define the terms based on the shared attributes of each group of shapes.

• Each group of 2 needs the set of cards from the previous activity, including the shape name cards.

• Groups of 2
• Each group should have access to their cards from the previous activity.
• Give each group a set of category cards (triangle, pentagon, hexagon, quadrilateral) from the Shape Cards blackline master.

• “The groups of shapes we created in Activity 1 have names. You may already know some of these names. Some names you may not know.”
• As needed, read the category names with the class.
• “As a class, your job is to gather clues to figure out which shapes go with each category name.”
• “First, each group will ask me if a card at your table belongs with a category. If it does, I’ll say ‘Yes.’ If it does not belong, I’ll say ‘No’ and give you a clue.”
• “Choose a card with your partner. Try to pick a card that might give you a clue. If another group asks about your card, quickly choose a different card.”
• 30 seconds: partner discussion
• Select students to ask a question. If the card does not belong with the category, respond with:
  • “No. It is not a _____ because it has __ sides and __ corners.”
• “Now that you have some clues, use the sentence frame to tell the class a shape, the name of the category it belongs to, and why based on the number of sides or corners.”
• 1 minute: partner discussion
• Select groups to make a statement. As needed, consider asking:
  • “Can a group name a shape that is a _____ (pentagon, hexagon, quadrilateral)?”

• “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 sides and 4 corners. A pentagon is a shape with 5 sides and 5 corners. A hexagon is a shape with 6 sides and 6 corners.)  
• Share and record responses.
• Display the shapes from the last question.
• “Would these 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.)

The purpose of this activity is for students to recognize and describe the attributes of triangles, quadrilaterals, pentagons, and hexagons. Students may describe many different attributes of the shapes, but connections to the shape names, number of sides, and number of corners are the most important points. As students work, encourage them to refine their descriptions of their shape using more precise language (MP6).

• Each group of 2 needs a set of cards from the previous activity.

• Groups of 2
• Each group should have access to their cards from the previous activity.

• “Pick one shape card. Think about how you would describe your shape to a partner without naming it.”
• 1 minute: quiet think time
• “You’re going to find a partner and describe your shape without showing them your card. Your partner will guess the name of your shape using triangle, quadrilateral, pentagon, or hexagon.”
• “After you both name the shapes, find one way your shapes are alike and one way they are different.”
• Give a signal for students to find a partner.
• 2 minutes: partner discussion
• “Trade cards with your partner. Find a new partner and play again.”
• Give a signal to find a partner.
• 2 minutes: partner discussion
• Monitor for students who describe how their shapes are alike and different based on the number of sides and corners.

If students describe their shape using words that don't make it clear to their partners, 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)