Lesson Plan
Shape Talk With Sides Corners and Curves Lesson Plan
Students will describe 2D shapes using sides and corners or curves and sort shapes into groups by a stated attribute with teacher support.
Understanding shape attributes is a fundamental building block for geometry and spatial reasoning. This lesson helps students develop precise mathematical language to articulate what they observe about shapes in the world around them.
Audience
Kindergarten
Time
30 minutes
Approach
Hands-on activities and discussion.
Materials
Large 2D Shape Cut-outs (Circle, Square, Triangle, Rectangle, Hexagon), Craft Sticks, String or Yarn, Mixed Shape Cards (various 2D shapes), Sides Corners Curves Visuals, Build-a-Shape Sticks and Strings Center, Sort by Attribute Mat, Which One Doesn’t Belong Prompts, and Oral Math Language Look‑Fors
Prep
Teacher Preparation
15 minutes
- Review the Shape Talk With Sides Corners and Curves Lesson Plan and all linked materials: Sides Corners Curves Visuals, Build-a-Shape Sticks and Strings Center, Sort by Attribute Mat, Which One Doesn’t Belong Prompts, and Oral Math Language Look‑Fors.
- Cut out large 2D shapes (circle, square, triangle, rectangle, hexagon) for introduction.
- Gather craft sticks and string/yarn for the 'Build-a-Shape' activity.
- Prepare mixed shape cards for sorting.
- Print or display the Sort by Attribute Mat.
- Prepare discussion prompts from Which One Doesn’t Belong Prompts.
Step 1
Introduce Shape Attributes (5-7 minutes)
5-7 minutes
- Display large 2D shape cut-outs.
- Teacher says: "Today we're going to become shape detectives! We'll learn how to talk about shapes using special math words."
- Introduce 'sides': "These are the straight edges of our shapes. Let's count the sides on this square." (Count together). "Does a circle have straight sides?"
- Introduce 'corners': "Where two sides meet, we have a corner." (Point to corners on a square/triangle). "Do circles have corners?"
- Introduce 'curves': "Some shapes don't have straight sides or corners, but they have curves!" (Trace the curve of a circle).
- Use the Sides Corners Curves Visuals to reinforce vocabulary and show examples.
- Ask students to identify sides, corners, or curves on different shapes you hold up.
Step 2
Build-a-Shape Activity (10-12 minutes)
10-12 minutes
- Distribute craft sticks and string/yarn to students or small groups.
- Teacher says: "Now you get to be shape builders! Use your craft sticks to make the sides of a shape, and your string to make curves or to outline a shape."
- Guide students to build specific shapes (e.g., "Make a shape with three sides and three corners." or "Make a shape with a curve.").
- Circulate and prompt students to describe their creations using the new vocabulary. "Tell me about the shape you built. How many sides does it have? How many corners? Does it have any curves?"
- This is the Build-a-Shape Sticks and Strings Center.
Step 3
Sort by Attribute (8-10 minutes)
8-10 minutes
- Provide students with mixed shape cards and the Sort by Attribute Mat.
- Teacher says: "Now we're going to be shape sorters! I will tell you a rule, and you will sort your shapes into groups that follow the rule."
- Start with a simple rule, e.g., "Sort your shapes into two groups: shapes with straight sides and shapes with curves."
- After students sort, ask them to explain their reasoning. "How did you sort your shapes? Why did you put these shapes together?"
- Introduce another rule, e.g., "Sort your shapes into shapes with 3 corners and shapes with more than 3 corners."
- Observe student understanding and use the Oral Math Language Look‑Fors for assessment.
Step 4
Debrief: Which One Doesn’t Belong (5 minutes)
5 minutes
- Display a set of shapes (e.g., 3 triangles and 1 square, or 3 shapes with straight sides and 1 circle) from the Which One Doesn’t Belong Prompts.
- Teacher says: "Look at these shapes. Which one do you think doesn't belong with the others? Why? Remember to use our math words: sides, corners, and curves!"
- Facilitate a brief discussion, encouraging students to justify their answers using shape attributes.
- Summarize key learning: "Great job, shape detectives! Today we learned to describe shapes by their sides, corners, and curves, and we used those ideas to sort them!"
Slide Deck
Shape Talk Detectives!
Let's explore the world of shapes!
Welcome students to the lesson. Introduce the idea of being 'shape detectives.' Briefly review familiar shapes.
What are Sides?
👉 Straight edges of a shape.
Let's count them!
Explain what 'sides' are: the straight edges. Use your finger to trace the sides on a real-life example or a large shape cutout. Count them together.
Shapes with Sides
How many sides can you find?
Show examples of shapes with sides (square, triangle, rectangle, hexagon). Ask students to identify and count the sides on each.
What are Corners?
👉 Where two sides meet.
Do all shapes have corners?
Explain what 'corners' are: where two sides meet. Point to corners on the same shapes. Emphasize that circles don't have corners.
Shapes with Corners
Can you spot all the corners?
Show examples of shapes with corners. Ask students to point to and count the corners on each.
What are Curves?
👉 A rounded line.
Some shapes have curves instead of straight sides!
Explain what 'curves' are: rounded lines. Trace the curve on a circle. Contrast with straight sides.
Shapes with Curves
Which shapes have curves?
Show examples of shapes with curves (circle, oval). Discuss how they are different from shapes with straight sides and corners.
Shape Detective Challenge!
Tell me about this shape:
- Does it have sides?
- Does it have corners?
- Does it have curves?
Review all three attributes. Ask students to describe various shapes using 'sides,' 'corners,' and 'curves.'
Activity
Build-a-Shape Sticks and Strings Center
Objective: Students will construct 2D shapes using craft sticks and string, and describe their creations using the terms 'sides', 'corners', and 'curves'.
Materials:
- Craft sticks (various lengths if available)
- Pieces of string or yarn
- Sides Corners Curves Visuals (for reference)
Instructions:
- Introduce the Center: Gather students and explain that they will be shape architects! Show them the craft sticks (which they will use to make straight sides) and the string or yarn (which they will use to make curves or to outline the whole shape).
- Guided Building (5-7 minutes): Start with a challenge. Ask students to build a shape with a specific number of sides and corners. For example:
- "Build a shape with 3 sides and 3 corners." (Expected: Triangle)
- "Build a shape with 4 sides and 4 corners." (Expected: Square or Rectangle)
- "Build a shape with no sides and no corners." (Expected: Circle or Oval using string)
- Free Exploration (Optional, 5 minutes): After the guided examples, allow students time to freely create their own shapes using the materials. Encourage creativity!
- Describe Your Shape (Ongoing): As students build, circulate and prompt them to describe their creations using the target vocabulary:
- "Tell me about the shape you built. How many sides does it have?"
- "How many corners can you count on your shape?"
- "Does your shape have any curves? Where?"
- "How is your shape different from your partner's shape?"
- Clean Up: Remind students to return all craft sticks and string to the designated area.
Worksheet
Sort by Attribute Mat
Name: _____________________________
Instructions: Cut out the mixed shape cards (provided by your teacher). Sort them onto this mat based on the rule your teacher gives you. Then, explain your sorting rule.
Group 1:
Group 2:
My Sorting Rule Was: ____________________________________________________________________
I sorted my shapes by:
Discussion
Which One Doesn’t Belong? Shape Talk Discussion
Objective: Students will verbally justify their reasoning for why a shape doesn't belong, using descriptive math language (sides, corners, curves).
Instructions: Display one of the sets of shapes below. Ask students: "Which one doesn't belong? Why?"
Encourage students to use the words 'sides', 'corners', and 'curves' in their explanations.
Prompt 1:
Shapes: Three triangles and one square.
Teacher Prompts:
- What do you notice about all of these shapes?
- How are the triangles alike?
- How is the square different?
- Can you describe the square using our new words?
Prompt 2:
Shapes: Three shapes with straight sides (e.g., square, rectangle, triangle) and one circle.
Teacher Prompts:
- What is special about the circle compared to the other shapes?
- Does the circle have sides or curves?
- Do the other shapes have sides or curves?
Prompt 3:
Shapes: Three circles and one oval.
Teacher Prompts:
- How are all of these shapes similar?
- What is slightly different about the oval?
- How would you describe a circle using curves?
- How would you describe an oval using curves?
Rubric
Oral Math Language Look-Fors Rubric
Objective: To assess students' ability to describe 2D shapes using mathematical vocabulary (sides, corners, curves) during discussions and activities.
| Criteria | Beginning (1 Point) | Developing (2 Points) | Proficient (3 Points) |
|---|---|---|---|
| Uses Vocabulary | Rarely uses words like 'sides', 'corners', 'curves'. | Uses 1-2 vocabulary words, sometimes incorrectly. | Consistently uses 'sides', 'corners', 'curves' correctly. |
| Describes Shapes | Describes shapes generally (e.g., 'round,' 'pointy'). | Attempts to describe shapes with attributes, but may need prompting. | Clearly describes shapes using specific attributes (e.g., 'It has 3 sides and 3 corners.'). |
| Explains Reasoning | Struggles to explain how shapes are alike/different. | Explains reasoning with some support, may use gestures. | Clearly explains reasoning for sorting or identifying attributes. |
| Participation | Reluctant to participate in discussions. | Participates when prompted, sometimes with hesitation. | Actively participates and shares ideas confidently. |
Teacher Notes:
- Use this rubric to observe students during the Build-a-Shape Sticks and Strings Center, Sort by Attribute Mat activity, and Which One Doesn’t Belong Prompts discussion.
- Focus on capturing authentic language use.
- A checkmark or brief note in each column can indicate student progress.