We’ve been talking geometry in class recently. We’ve discussed polygons (Mrs. Yollis class has a great post about them), angles, and now circles.

We began by reviewing all the different parts of a circle. In the picture above, you’ll see a green line segment extending fro the center point of the circle to the edge of a circle. This is called the **radius**. The red line segment extending from one side of the circle to the other while also going through the center point is our **diameter**. Much like the radius, the diameter MUST always go through the center of the circle. The diameter is always twice the size of the radius so we can find it by using the formula** d=2r**. Likewise, because the radius is half the size of the diameter, you can find that by doing** r=d รท 2**.

There are also other parts to a circle as well. The purple line segment is called a **chord**. The chord must also have two points on the edge of the circle but does not have to go through the center. You also have the yellow shaded in part which is called the **sector**. The sector is a section of the circle created between to radii and an arc (the arc is a portion of the outside of the circle).

The whole outside of the circle is called the **circumference**. If you were to cut the outside of the circle and lay out out in a straight line, the diameter would fit into the circumference about 3.14 times. This is a number that is referred to as pi. It is often shown using the symbol ฯ. Based upon the relationship between the diameter and the outside of the circle, we can find the circumference by using the formula C = dฯ.

Sam, Fiona, Wes, and Ryan from the math movie network set out to make sense of circles and more specifically, circumference. The video below will share with you the meaning of pi as well as how to use it to find the circumference of a circle!

**What are some of the different places you find circles in everyday life?**

**Does circumference make more sense to you now?**

Dear Mr. Avery,

I think we all did a great job on circles! ๐ I REALLY REALLY REALLY want to make pie charts this year! I hope you have a great day!

check out my blog sometime please at http://tessatime.edublogs.org/

Sincerely,

Tessa

Dear Tessa,

I agree. I hope everyone enjoyed our Circle Hunt today! My class will be doing it tomorrow. I’m hoping we can get some pictures so we can write a post about it. We’re way overdue on a new post! Also, next week I’m hoping your class can do a MMN video on finding the area of a circle.

Sincerely,

Mr. Avery

Dear Mr. Avery’s class,

This reminds me of what we learned about the radius last year. We never knew about the circumference before we watched your video. We would like to learn more. The thing that you had on the board reminded me of a chalk line that you put on the wall to put a boarder around your room. You lay the string along the wall and pull it out then let go. When the string hits the wall, it leaves a straight chalk line.

Sincerely,

Your Techie Kids

Ashley and Rachel

Dear Mr. Avery and Class,

This is important because we learned about circumference. Pi reminds us of pie. We never knew how to do this.

Sincerely,

Rebecca, Autymn & Emma

Techie Kids

Dear Mr. Avery and class,

We never knew that geometry was so interesting. We wonder why the symbol for pi is greek. We thoght we might know becasue we know a lot about greek. Geometry is a little confusing and a bit hard to follow, but your video made it much clearer. We hope you guys enjoy your geometry lessons!

From,

Jackie and Grace,

the Techie Kids

Dear Mr. Avery & Class,

I Really loved the math video! It helps us learn a lot. We haven’t learned much yet but we will soon. There are lots of circular shapes that you can see around Michigan…For instance You will find a clock, Place Mat, Rug,And much more. And yes, Circumfrence does make a TON more sense after we whatched your video! This video reminded me of my 4th grade year when we were learning a lot more about Circumference and Circle information. This is important to our class and I because we will already know some information for 6th grade! Thanks for all you share! ๐ ๐

Happy Blogging,

Emma

Techie Kids

Dear Mr. Avery’s class,

We learned a lot about Circumference! That’s interesting! We never knew that we would learn that. This remids me of fractions and pie charts. This would be important because, later we would need to know all about different kinds of ways to do math! We wonder when we are going to learn this. It sounds pretty easy!

Sincerely,

Techie Kids,

Rachel and Sydney

Dear Mr. Avery’s class,

Thank you for all of the wonderful information about Circumference. I can really use all of this information in school and probably for the rest of my life. I never knew that math could be so interesting. This reminds me of pie charts and fractions. I wonder if there could be an impossible problem to do out there? I’m going to tell my parents all about Circumference. I think that all of your Math Movie Network vidoes are awesome, great, the best, and most of all, out of this world amazing!

Cyber High Fives,

Juliana a Techie Kid

Dear Mr. Avery’s class,

We never knew what circumference was so we watched your video. Now we know more about it. What means the most to us is that we also learned about diameters. This reminds me of what we kinda learned in math class last year. This is important to us beacuse in fourth grade we talked about a radius. We looked around the room and saw different circles. We found cups, CD’s, and a clock. I wonder if we will learn more about this in sixth grade.

Sincerly,

Your techie friends,

Holly, Megan, and Kenzie

Techie Kids

Dear Mr. Avery’s Class,

You guys did a great job on the video! We wish we could have something like that on Techie Kids! We have to say that was a pretty clever idea. Even though we haven’t learned about circumfrence and pi, it helped us a lot. We just want you to know that you did a terrific job on that wonderful, informative, video.

Have A Great Day,

Jenna, Kora, and Sami:]

Techie Kids

Dear Mr. Avery’s class,

We thought the video was fantastic! This taught us a little more about circumfrence, diamater, radius, and pi. This reminds us about a book we read in 4th grade called Sir Comfrence and his Adventures. It taught us the same idea as your class taught Monique and I on the video except that there was a man named Sir Comfrence that has to measure the sun with a compass to open the secret door and exit. This book is in the Fantasy genre.

Cyber High-Fives,

Monique and Claire ๐

Techie Kids

Dear Mr. Avery,

I loved the video! I never knew how to do what you put in this video! I remember doing a little on this topic last year, but not this year. Thank you for teaching me this!

Sincerely,

Connor(Sir Cumfrence) & Nick,

Techie Kids

Dear Mr. Avery,

This reminds me of a pie graph that I learned about in fourth grade. When I was in math, the teachers decided to tell us that we are doing a pie graph which we were kind of stumped when we saw the pie graph. Now we are pretty good at doing pie graph’s.

PS.I like the video

Sincerely,

Luke & Zach..

Dear Mr. Avery,

We learned a lot about circumference, radius, diameter, and chord. I never knew this much about the circumference. I wonder if theres more stuff about the circumfrence.

Sincerly,

Techie Kids

Dear Mr. Avery,

The video was really cool and at first I was confused but now I get the pi thing with the circumfrence and everything. Keep up the good work.

Your Student,

Frankie

Dear Mr. Avery,

I never knew circles could be so complicated! When we were little circles were just… circles, just plain old circles. Then, we get into 6th grade and all of a sudden circles have so much more. I understood it, but it was a surprise to me. Like, I knew that circles had a radius and a diameter but chord, sector, and arc? I didn’t know any of that! Plus, I always thought “PI” was high school stuff! But, I guess that’s what school’s for. ๐

Sincerely,

Molly C.

Dear Mr. Avery and 6th Grade Class,

Nice job on the video! I was kind of confused with the whole pi thing, but now that I watched the video, I am understanding it better. Keep up the good work, and I can’t wait to see what videos we will come up with next. Happy blogging!

~ Emma W.

Dear Emma,

Thanks! We’ll be doing a little work in the gym when we come back from vacation to help us learn about circumference. I think it will definitely help us understand pi a little bit better! We’ll definitely watch this video too in order to help us a little bit better.

I’m looking forward to making some more videos when we come back from vacation. What else do you think we should make some videos about?

Sincerely,

Mr. Avery