It seems like forever ago but I wanted to finally blog about the success of the Discovering Pi/Discovering Circumference formula project I did with my students.

I used this as a warm-up to squash any questions students may have had about vocabulary etc.

That took about 5-10 minutes for us to answer as a class and reinforce the correct answers and why. I also made a point to let students know that they should pay attention or take notes because they would need to know all these things to successfully complete the project. I also explained that this project would count as a quiz grade and an opportunity to boost their averages. These were all (bribes?) incentives for students to engage with the project and do their best.

I handed out the worksheet and read the directions out loud. I also read the rubric out loud for students with a strong emphasis on the FOCUS ON TASK points. I passed out supplies or in some classes I let students help me pass out supplies. We don’t have enough scissors or glue so students had to share those but each student got 2 different sized pre-cut circles and two different colored pieces of yarn.

*I would probably not use yarn if I were to do this again, it stretches and makes a lot more opportunity for measurement error. I used yarn for a prettier poster option but in hindsight something without stretch would be better.*

I also put a giant grid on the white board for students to put their name and their two decimal answers up on the board when they completed their calculations and before they could get construction paper. In the last 10 minutes of class we looked at the results on the board and at least one student in each class recognized we were awfully close to pi.

I then wrote C/D = pi and then solved for C = pi*D, and then we discussed radius and diameter and substituted and got C = 2*pi*r. A lot of students were shouting out “pi-r-squared” but when we got the end they were able to see that the circumference formula is not “pi-r-squared,” and why. They did identifying radius, diameter, and find the circumference procedures for homework and do-now’s the next day.

Worksheet:

Students got so creative and were so engaged and here are some of the results: