Lesson 5
Circles and Triangles
Lesson Purpose
The purpose of this lesson is for students to identify, describe, and compare circles and triangles.
Lesson Narrative
Students are also introduced to the geometric terms circle and triangle. Students develop their intuitive understanding of circles and triangles. They may incorrectly identify shapes in this activity, such as identifying an oval as a circle. If this happens, acknowledge the similarities between the shapes (“This shape is curved like a circle, but it is not a circle.”) As students sort examples and nonexamples of triangles in the second activity, they continue to build their informal understanding of what a triangle is.
 Representation
 MLR8
Activity 2: Triangle Sort
Learning Goals
Teacher Facing
 Identify, describe, and compare circles and triangles.
Student Facing
 Let’s learn the names of some shapes.
Required Materials
Materials to Gather
 5frames
 Collections of objects
 Colored pencils or crayons
 Counting mats
 Materials from previous centers
Materials to Copy
 Triangle Sort Cards
Required Preparation
Activity 1:
Each student needs at least 2 different colored crayons or colored pencils.
Activity 2:
 Cut out triangle cards from the blackline master. Each group of 4 needs 1 set of cards.
Activity 3:
 Gather materials from:
 Which One, Stage 1
 Picture Books, Stages 13
 Bingo, Stages 1 and 2
 Shake and Spill, Stages 1 and 2
Lesson Timeline
Warmup  10 min 
Activity 1  10 min 
Activity 2  15 min 
Activity 3  20 min 
Lesson Synthesis  10 min 
Cooldown  0 min 
Teacher Reflection Questions
How did students think of triangles as they came into the lesson? In what ways did their understanding of triangles change upon completing the lesson?
Print Formatted Materials
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Additional Resources
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