Bucknell University – UBD Lesson Plan

Circumference and Arc Length

Teacher_Nathaniel Nauman__________ Grade__9th and 10th_____________

Date_Feb. 12, 2013__________________	Subject__Geometry____________

Stage 1- Desired Results
Established Goals: G G.2.2.2.2 - Find the measurement of a missing length, given the perimeter, circumference, or area. G.2.2.2.4 - Develop and/or use strategies to estimate the area of a compound/composite figure.
Understandings: U Students will understand… how to calculate the circumference of a circle and why this information is valuable. how to calculate the arc length of a circle and why this information is valuable.	Essential Questions: Q What is the circumference and arc length of a circle? How are they calculated? How can this knowledge be applied in the real world?
Student will know…. K the formula for the circumference of a circle the formula for the arc length of a circle	Student will be able to… S calculate the circumference of a circle when given its radius or diameter calculate the radius or diameter of a circle when given its circumference calculate the arc length on a circle when given the radius or diameter of a circle and the measure of the arc
Stage 2- Assessment Evidence
Performance Tasks: T Calculate the degrees that a gear in a watch must turn in order to fully rotate another gear in a watch twice.	Other Evidence: OE Focus question, practice problems throughout the lesson, various questions and homework problems.
Self-Assessments	Other Evidence, Summarized
Stage 3 Learning Plan
Learning Activities: L Start lesson with a focus question on the slides that students will need to work on and answer. Then work through the PowerPoint Slides. Start by using an activity to engage students and make them think and realize several important facts about circles, in particular, that the circumference of a circle is basically the perimeter of a circle. After this is done, introduce how to calculate the circumference of a circle through discussion when given the diameter or radius of a circle. Then work on some practice problems where students need to calculate the circumferences of circles when given the radius or diameter. After this, move on to an application problem where the circumference of a tire is provided and students need to calculate the radius of the tire. Confirm that students understand this material and then move on to introducing and explaining what the arc length is and how it is calculated. After confirming that students understand this material, move on to a couple of practice problems where students need to calculate the length of an arc in a circle and the radius of another circle. Then finish the lesson by having students work on an application problem involving an arc length of a gear in a watch. Extension: Cut a paper into a circle and use it to explain circumference in terms of its diameter and radius, if necessary, or arc length by cutting a piece out of the circle and explaining using what the students know about circumference of a circle and angle measures in a circle. Resources: White Board, Markers, White Board Erasers, SmartBoard, Projector, PowerPoint Slides, Compasses for students, Rulers for students, paper, scissors and the homework assignment papers.