Lesson 3

This warm-up prompts students to compare four images of shapes. It gives students a reason to use language precisely (MP6). It gives the teacher an opportunity to hear how students use terminology and talk about attributes of the shapes in comparison to one another. During the synthesis, ask students to explain the meaning of any terminology they used, and if it does not come up, remind them of the term “square corners.”

• 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.

• “What makes Shape A different from the others?” (It doesn’t have square corners.)
• “How can you tell it does not have square corners?” (A square wouldn’t fit in any of the corners in Shape A.)

The purpose of this activity is for students to identify and draw shapes that have specific side lengths. Students practice measuring in inches and centimeters. Students recognize that triangles, quadrilaterals, pentagons, and hexagons may look different when only some sides are the same length. 

• Groups of 2
• Give each student a ruler.

• “We are going to think more about shapes by measuring their sides. Use your ruler to identify and draw the shapes.”
• 7 minutes: independent work time
• “Compare the shapes you drew with your partner’s shapes.”
• 5 minutes: partner discussion
• Monitor for a variety of examples of Priya’s shape to share in the synthesis.

If students' measurements are not the length of the given sides when measuring or drawing shapes, consider asking:

• “Can you show me how you measured the sides of this shape?”
• “How can you use the ruler to make sure the side is 2 inches long?”

• Select 2–3 previously identified students to share, or draw some examples, such as:

  

  

• Consider asking, “What is the same about these shapes? What is different?”
• “Why were we able to draw so many different shapes even though you had to use a certain length?” (Only one side had to be 2 inches. We could draw shapes with different numbers of sides.)

The purpose of this activity is for students to recognize and draw shapes that have a specific number of sides and corners, and specific side lengths. Students deepen their understanding that shapes in the same category can share many attributes and look different. Students also notice that some attributes can’t go together to form a shape (for example, a shape can’t have 3 sides and 4 corners, or 3 sides and all square corners).

Students may persevere in problem solving if they look for or choose particular attributes that do not go together (MP1). In some cases, such as a shape with 3 sides and 4 corners, they may be able to see right away that no such shape exists. But in other cases, such as a shape with 3 sides and 2 square corners or 6 sides and all square corners, they will need to experiment and reason in order to predict that no such shape exists. 

• Groups of 2
• Give students access to rulers.
• Display the attribute table.
• “We have been learning about attributes of shapes. This table shows some of the attributes of shapes we have been thinking about, such as number of sides, numbers or types of corners, and specific lengths of sides.”
• Draw or display a rectangle with two sides that are 3 inches long.
• “What attributes do you think were picked from this table to draw this shape?” (4 sides, 4 corners, all corners are square corners, 2 sides are the same length. It’s either 2 sides are 2 inches or 2 sides are 3 inches long.)
• Circle the attributes that students identify on the attribute table.

• “Now you will get a chance to pick your own attributes, draw your own shapes, and guess which attributes your partner picked.”
• “If you have time, work with your partner to answer the last problem.”
• 5 minutes: independent work time
• 5 minutes: partner work time
• Monitor for:
  • a variety of triangles, quadrilaterals, pentagons, and hexagons
  • students who attempt to combine attributes that do not result in a shape

• Invite previously selected students to share the shapes they drew.
• For each, ask, “What attributes do you think they used to make this shape?”
• 30 seconds: quiet think time
• Share responses.
• Display student work that shows attributes that do not make a shape, or share attributes and display an image like the following:
  • 4 sides, 3 corners, 2 sides are 2 inches, 1 square corner
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• “Why do you think _____ couldn’t finish this shape?”