Circle Similarity Made Easy

Ways to Prepare to Teach Similarity in Circles

When teaching transformations, most teachers don’t begin with circles because students find it easier with shapes like triangles, quadrilaterals, and pentagons. However, using circles to show similarity may be easier than you think.

Prerequisites for Working with Circles

Before beginning, it's a good idea to do a quick review of the terms circle, radius, circumference, and scale factor.

A lessons’ opening is not busywork. It should always incorporate a review of previously taught skills or an introduction to the current lesson. The bellringer mentally prepares students for the lesson.

Making Connections

Circles are figures on a plane where all points are equal distance from a center point — proving that two circles are similar mean understanding the type of transformation used on the original or primary circle. In teaching this, you can use drawings, discuss verbal examples, or compare objects found around the room.

Usually, to find out the transformation of the original circle, students need to search for the scale factor due to the difference in size between two circles. Be sure to connect the visual of different sized circles with the math involved in finding the scale factor.

Similarity in Circles Lesson Plan

In the “Similarity in Circles” lesson plan, you will find an activity that utilizes balloons and wires to demonstrate how two same shaped objects can similar by blowing the balloons up different sizes. It is also a visual example of how to measure the scale factor between objects.

Included in this free lesson plan are activity instructions, a bellringer, an exit pass assessment, and a presentation to go over with your students to make sure they understand the vocabulary and concepts.

Take advantage of using exit passes as a quick assessment of how effective the lesson was.

Click now for your chance to download this free “Similarity in Circle” lesson plan. It already has the common core standards marked is waiting for you to try it out.

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