Radius, Diameter, and Circumference

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SWBAT identify the parts of a circle and calculate radius and diameter of circles.

Big Idea

Students work with partners and check in with teacher to introduce circles and the relationships between radius, diameter, and circumference

Do Now

15 minutes

Students enter silently according to the Daily Entrance Routine. They find Do Now assignments and clickers at their desks. Students will be given 10 minutes to answer 10 questions including rational number operations. At the end of 10 minutes, I will ask them to enter their answers into SMARTResponse clickers. Once they are finished (2 – 3 minutes). They will be advised that this type of test will become a quiz for a grade on Wednesday, thus giving them two days’ worth of practice to improve and earn the best grade possible. I use the data created by the clickers to review the lowest scored question. Students who do not finish in ten minutes will be expected to improve with additional practice the next two days. I keep extra problems in a designated spot in the classroom for students to retrieve on their own. These resources are parts of a Glencoe workbook available online. 

I explain to students that in order to improve they must push themselves to complete 10 problems in 5 minutes. First they need to focus on completing the ten questions without paying mind to write and wrong, but also trying at least one step in each questions.  Each sheet has about 30 problems, offering three different opportunities per sheet to practice in 5 minute spurts. I will have answer documents and students can ask for one to check their answers.

I’ve made sure to include questions with fractions and long division for the next two days on this assignment; these are two skills many of my students are still struggling to master. The “bonus” question is taken from a practice SSAT book to push higher students.

I introduce out “Mid-Year Challenge” as a motivator for the return of the winter break. The student with the highest average and the student with the greatest improvement in points from the Q2 progress report to the end of Q2 grade will earn a prize. The PowerPoint includes only a picture of the bag the prizes will come inside of, but I plan to fill each bag with puzzles, games, and other crafts/supplies from oriental trading. I’ve attached an image of the small prizes I plan to place in each prize-bag 

Class Notes + Practice

25 minutes

Students will receive calculators and class notes in the form of a copy of the key slides from the power point presentation (slides 2, 8-9, 11-13). These slides review the parts of a circle and formulas of circles. Next, they are asked to turn to a neighbor to review the information in the next two slides which detail that relationship between radius and diameter (d = 2r). I push understanding of basic definitions by asking the following questions:

  • What is circumference?
  • How are radius and diameter related?

Next, students are asked to work with neighbors to complete the table in slide 11. We move on to slide 12 together and I ask for students to participate the missing radius and diameters in that slide. Then explain the meaning of leaving an answer “in terms of pi” and what this number represents. Often, students will confuse the symbol π for unit. For example, in a circle with radius 3 inches, they may answer 9π^2, squaring the pi symbol rather than the unit “in ^2”. Students may also think that in a circle with circumference 10

Exit Ticket

10 minutes

Once there are 10 minutes left in class students will be asked to complete the exit ticket in their PowerPoint packet, detach the sheet once they finish and turn it in at the end of class. I will be using this sheet to evaluate whether or not students understood a commonly misunderstood concept of measurements in terms of pi mentioned in the notes. This question will help me assess student progress within MP1 as they make sense of an irrational number, and why it is used with circles. Students who do not include work will be pulled for lunch. Students who provide work and make small errors will receive their exit ticket with feedback and directions to find and fix their error. Students receive their HW sheet after they turn in their exit ticket.