# 31 Mile Wide Hula Hoop (10/7/14)

So last week on Twitter I saw this post, and immediately thought, “No Way!” But after crunching some numbers it actually seemed feasible. So today I threw out the question to my geometry classes today. I started with a small hula hoop and asked them how many of them could stand comfortably inside of it. Then we used a slightly larger one and did the same thing. Then I asked them to estimate how large of a hoop we would need for all 1,200 students at our school to stand comfortably inside, then I dropped the big question on them, “What size hula hoop would we need to fit every person on the Earth?”

There was an immediate reaction and students started throwing out crazy numbers. Some said 250 or 500 miles wide, some said a hoop the size of Texas, some said a hoop with a diameter across the US, some said the size of Asia, crazy estimates but they were all really enthusiastic! Now I asked them what info they needed to solve the problem and they told me the population of the Earth, so I gave it to them. At this point the students were literally fidgeting in anticipation of getting started. I told them that I hoped they had some kind of plan in their heads about how they could figure this out. Then I said, “Go.”

What followed was what we all dream about happening in our classes. Students grouping together and diving head first into solving a problem. Some grabbed yard sticks and rulers and started measuring their feet and carpet squares. Some grabbed measuring tape and started measuring me (width of my shoulders, circumference of a circle around my feet, etc), thinking that I better represented an average human than them. It was great.

They pounded away on their calculators and scribbled numbers on whiteboards and scratch paper. Unfortunately, we ran short on time just as some groups were beginning to come up with answers. We don’t have school Thursday or Friday and because of block days this was the last time I’ll see them until Monday. They begged me to tell them the answer, and I gave in and told them. They were downright shocked. I gave them a reference of how far 31 miles was in terms of our city and they couldn’t believe it.

This happened in both of my geometry classes today. It was a seriously amazing. It’s a great reminder that the right problem can help my classroom become the place that I always strive for it to be. Awesome day.