The Official Blog of 8C

Jan 09

Circle: Circumference and Area GIZMO

General No Comments »

Watch this Video first! Oliver with a Twist

Then complete this Gizmo. Read all the instructions

Exploration Guide » Circle: Circumference and Area

In the Gizmo^tm, use the slider to set Radius (r) to 6.0. (To quickly set a value, type a number in the box to the right of the slider and press Enter.)
1. What line segment in this circle measures 6.0? (The line segment itself is not pictured in the Gizmo.)
2. Since the radius has a length of 6.0 units, what is the length of the diameter in this circle? Click on Show diameter to check your answer.
3. The formula for the area of a circle is A = πr². Which value do you use in this formula, the radius or the diameter? What does r² mean?
4. Describe in your own words what the formula A = πr² tells you to do to find the area of a circle.
5. Since π is a decimal that does not end or repeat, it is helpful to use approximations for it. To estimate your answer for the area of a circle, you can use 3 as an estimate for π. What is the approximate area of this circle, with r = 6.0, using 3 for π? Click on Show area info, and look under A to see how close your estimate is to the actual area.
6. Estimate the area of a circle with r = 2.0. What is your estimate? Use the Gizmo to find the actual area.
Turn off Show area info and Show diameter. Set Radius (r) to 9.0.
1. Use 3 for π and estimate the area of this circle.
2. Use a calculator and the formula A = πr² to find the area of this circle. After you squarer, multiply r² by π, using the π button on the calculator. Round your answer to the nearest tenth. What is your answer? How does your answer compare with your estimate of the area?
3. Click on Show area info. How does your answer for the area of the circle compare with the Gizmo?
4. Use a calculator and the formula A = πr² to find the area of a circle with radius 8 cm. Round your answer to the nearest tenth. Check your answer using the Gizmo.
5. Find the area, rounded to the nearest tenth, of a circle with diameter 22 meters. What do you need to do first, in order to use the formula A = πr²? Click on Show diameter to be sure that you are using the correct value for r. Use the Gizmo to check your answer for the area of the circle.
When r is a multiple of 7, or is a fraction, it is sometimes easier to use a value of as an estimate for π.
1. Using the formula A = πr² and for π, find the area of a circle with radius 7 ft. After you have substituted 7 ft. in place of r and then squared it to get 49, be sure to simplify. (Hint: You can divide 7 and 49 by their greatest common factor, or GCF, 7.) What is your answer?
2. Using the formula A = πr² and for π, find the area of a circle with diameter 140 km. What do you need to do first? What is your answer?

Dec 12

November Book Response (December 19)

General 17 Comments »

Complete your November book response (Lit Letter) by December 19. Finish reading your book, then go to the Wiki >Book Talks to choose a Guideline template that is appropriate for your book (Plot, Character, Big Idea, or Personal).

You must use one of the Guidelines as a starting point.
DO NOT WRITE YOUR RESPONSE WHILE ON THE BLOG. COPY YOUR RESPONSE FROM A WORD PROCESSOR (EDIT AND REVISE). WRITING QUALITY IS IMPORTANT!
Don’t forget to look at the new book review guidelines. Give it a try!

****New****

Post your book response in a GLOG that you have made with your GlOGSTER ACCOUNT

On the BLOG (below) post the link to your finished GLOG. Tell us (on the blog below) which guideline you used. Your GLOG must include the text of your response and a picture of the cover of your book. Try recording your voice reading the response. Be creative. Feel free to add anything that will enhance and enrich your response (video, music, graphics, etc.).

Be sure to read your classmate’s book responses.

Happy Reading!

Mr. W.

Nov 12

October Book Response (November 21)

General 19 Comments »

Complete your October book response (Lit Letter) by November 21. Finish reading your book, then go to the Wiki >Book Talks to choose a Guideline template that is appropriate for your book (Plot, Character, Big Idea, or Personal). You must use one of the Guidelines as a starting point.
DO NOT WRITE YOUR RESPONSE WHILE ON THE BLOG. COPY YOUR RESPONSE FROM A WORD PROCESSOR (EDIT AND REVISE). WRITING QUALITY IS IMPORTANT!
Don’t forget to look at the new book review guidelines. Give it a try!
Submit a paper copy of your letter response to Mr. W by November 21. Post a digital version of your book response/review on our blog (right here). Your paper copy book response must have a parent or guardian signature. Be sure to read your classmate’s book responses.
Happy Reading!
Mr. W.

Nov 07