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# Human Conics: Circles and Ellipses

Lesson 3 of 13

## Objective: SWBAT define circles and ellipses as a locus of points and apply locus definitions to draw conic sections.

## Big Idea: Students collaborate with partners to become a human conic section and draw circles and ellipses using sidewalk chalk.

*50 minutes*

**Overview: **This lesson is adapted from the Human Conics lessons from the NCTM Illuminations website. I will be doing half of the lesson today with my students and the other half at a later time.

**Preparation:** For this first part of the lesson, students will need access to a compass. Later in the lesson, students will need sidewalk chalk and a rope (one piece, 10-12 feet long per group of 3 students). Human Conics, Supplies Needed.

**Narrative: ** As students enter class today they should begin working on questions 1-2 of the Human Circle Student Worksheet. (I am going to copy this back to back with the Human Ellipse worksheet which is located in next section of lesson). After about 5 minutes bring the class back together. Discuss how the parts of the compass relate to the parts of the circle. Emphasize the importance of not changing the width of the compass (the radius of the circle) by squeezing too tightly when using the compass. Also, emphasize that the definition of a circle describes the points on the circle, not the area inside.

Next, present the definition of an ellipse using Teacher Resource - Ellipse Definition. I am not planning on giving students a copy of the definition. I will project this resource under the document camera. I am going to use different colors on the paper to highlight the pieces of the definition. I will take this paper with us when we go outside in case any teams want to reference it while we are outside.

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#### Human Conics

*35 min*

Students will now venture outside (in Arizona we generally don't have to check the weather). Teams of three students will complete the tasks posed on the Human Circle and Ellipse handout. Each group will need to apply the definition of both conic sections (circle and ellipse) in order to draw these accurately with sidewalk chalk. I will be checking in with teams and to ensure their drawings are accurate. Students should start with the circle and then work on the ellipse.

I think this activity is going to be challenging for students to figure out how to work as a team to draw the conic sections. I am guessing there are going to be a lot of great student conversations going on.

I hope to see a lot of activity with respect to Mathematical Practice 3**: Construct viable arguments and critique the reasoning of others.**

##### Resources (11)

#### Resources

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#### Closure: Class Huddle

*5 min*

With about 5 minutes remaining in the class period, I am going to call students over to a huddle outside. I just want to collect student work now and also ask some closure questions of the class.

Here are the questions I will pose to students:

- How many people minimally does it take to draw a circle? An ellipse?
- What would happen if the rope was longer? Shorter?
- Are you able to draw these conics continuously (without picking up the chalk)?

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Thanks so much for posting this. I used this lesson today with my pre-calculus students. I live in Montana, so we didn't go outside to use sidewalk chalk, instead I just used pencils and big pieces of butcher paper. I was surprised and pleased at how well some of the students took to figuring out a way to draw an ellipse even with me only saying that an ellipse has two foci, where a circle has a center.

| 2 years ago | Reply##### Similar Lessons

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- UNIT 1: Basic Functions and Equations
- UNIT 2: Polynomial Functions and Equations
- UNIT 3: Rational Functions and Equations
- UNIT 4: Exponential Functions and Equations
- UNIT 5: Logarithmic Functions and Equations
- UNIT 6: Conic Sections
- UNIT 7: Rotations and Cyclical Functions
- UNIT 8: Cyclical Patterns and Periodic Functions
- UNIT 9: Trigonometric Equations
- UNIT 10: Matrices
- UNIT 11: Review
- UNIT 12: Fundamentals of Trigonometry

- LESSON 1: Cutting Conics
- LESSON 2: Name that Conic
- LESSON 3: Human Conics: Circles and Ellipses
- LESSON 4: Circles and Completing the Square (Day 1 of 2)
- LESSON 5: Circles and Completing the Square (Day 2 of 2)
- LESSON 6: Ellipses
- LESSON 7: Human Conics: Parabolas
- LESSON 8: Parabolas
- LESSON 9: Parabola Problem Partner Critiques
- LESSON 10: Hyperbolas
- LESSON 11: Non-Linear Systems of Equations
- LESSON 12: Conic Sections Test Review
- LESSON 13: Conic Sections Unit Test