Lesson 2

This warm-up prompts students to compare four shapes. It gives students a reason to use language precisely (MP6). It gives the teacher an opportunity to hear how students describe the attributes of shapes when comparing them. During the synthesis, ask students to explain the meaning of any terminology they use, especially regarding the use of “same” or “different” sides and 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.

• “Which of these shapes are pentagons? Explain.” (A, C, and D, because they each have 5 sides and 5 corners.)
• “Why is B not a pentagon?” (It isn’t closed. It only has 4 corners.)
  • Consider asking: “How many sides does it have? How many corners?”

The purpose of this activity is for students to draw quadrilaterals, pentagons, and hexagons and compare the attributes of different shapes that have the same number of sides. They continue to notice that shapes in these categories have the same number of sides and number of corners. They may describe differences in shapes that are in the same category based on the length of the sides and their orientation. They may also use informal language to describe differences in the corners of each shape (for example, square corners or “sharp” corners). Students learn to describe and measure angles formally in grade 4.

• Groups of 2

• “Today you are going to draw and compare shapes.”
• 5 minutes: independent work time
• Monitor for:
  • examples of shapes that have different side lengths, angles, and orientations to share in synthesis 
  • non-examples of quadrilaterals, pentagons, or hexagons
• “Compare your shapes with your partner’s shapes. Find one way your shapes are the same and one way they are different.”
• 4 minutes: partner discussion

If students draw shapes with a number of sides other than the number of sides that define the named shape, consider asking:

• “How do you know this is a ______ (quadrilateral, pentagon or hexagon)?”
• “How could you use the completed shape to help you draw another ______ (quadrilateral, pentagon or hexagon)?”

• Display 2–3 previously identified student examples of each shape.
• “What are the ways these shapes are different?” (different side lengths, different corners)
• If time, display non-examples of quadrilaterals, pentagons, or hexagons that students drew or display some examples, such as:

• “Would any of these shapes be a quadrilateral, pentagon, or hexagon? Why or why not?” (Sample response: No. The one on the far left has 4 sides and only 3 corners, so it’s not a quadrilateral.)

The purpose of this activity is for students to draw shapes that have a given number of sides or corners. Students then compare shapes based on their number of sides and corners.

• Groups of 2

• “Clare, Andre, and Han drew shapes. Using the clues, see if you can figure out which shapes might belong to each student. Then draw a different shape based on the clues.”
• 7 minutes: independent work time
• Monitor for examples of Han’s shape that have different numbers of sides, number of corners, side lengths, and angles to share in the synthesis.
• “Compare the shapes you drew with your partner’s shapes.”
• 5 minutes: partner discussion

If students circle only one shape or draw a shape with a number of sides or corners not meeting the criteria, consider asking:

• “How do you know this shape could be _____ (Clare’s or Andre’s) shape?”
• “Are there any other shapes that could be _____ (Clare’s or Andre’s) shape?”
• “How can you change your shape so it has _____ (fewer than 5 sides, 4 corners, or more than 4 corners)?”

• Display 2–3 previously identified student examples for Han’s shape.
• “How are these shapes different?” (different side lengths, different numbers of sides and corners)
• “Could each of these shapes be Han’s shape? Explain.” (Andre's shape has 4 sides and corners, so it could be any shape that has more than 4 sides and 4 corners. We could draw different shapes as long as they have more than 4 sides and 4 corners.)