Introduction to Circles

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SWBAT describe the relationship between circumference, diameter, and area of a circle

Big Idea

How big is that pizza?


5 minutes
  • POD

As students enter the room, they will have a seat, take out their Problem of the Day (POD) sheet and begin to work on the question on the SMARTboard. The POD allows students to use MP 3 continually based on the discussions we have about the problem each day.

  • Learning Target

The target for the day is also on the SMARTboard each day when students enter the room.  The target for today’s lesson is for students to describe the relationship between different parts of a circle.

To introduce our work with circles, we will do an exploratory vocabulary activity. I want to see what students know and remember about circles. As we look at the vocabulary we can discuss examples of each term and where students may have experienced the term outside of the classroom. After the SMARTboard activity, they can add the terms to their notes using the vocabulary form.


30 minutes

To continue the introduction to circles, students will do an exploration with measuring circles and making comparisons. Each table will get random circles that they can fold and measure. The circle will include several sizes of paper plates, pizza box inserts, and other circles that I cut. I want students to have lots of different sizes so they don't all have the same circle to work from in this activity. They will also get string to measure the circumference of their circles to use to make comparisons. Students will fold each of their circles to find the point of intersection at the center. They will use the measurement across the circle, through the point of intersection to identify the diameter. They will use the measurement from the point of intersection out to the edge to identify the radius. I want them to measure repeatedly to see that the radius and diameter are the same regardless of what point you chose on the circle. The goal is for student to see the relationship between the diameter of the circle and the radius of a circle. I also want them to see a relationship between the radius and the circumference of the circle to determine an approximation for pi. I want them to develop a formula for the circumference of a circle.


5 minutes

To end class I want students to use the Traffic Light strategy to give me an idea of how comfortable they are with discussing the formula for circumference. The activity today was to introduce them to the concept and help them develop understanding of what circumference is and how to find it. I need to know where we are with that and how to proceed based on their feedback.

Tell me how comfortable you are with describing how to find the circumference of a circle.

RED: I have no idea what you’re talking about Dr. Jackson

YELLOW: I can describe it with some help or support

GREEN: I’m good. I can describe it in my sleep.