As we celebrate Pi day, one must ask ourselves what is Pi really? Different people may say different things. Some say apple and pecan, some say 3.14. This is the most common answer that teachers get from the students. They all know 3.14, but they do not understand what it really means. Pi is not just some random numbers that teachers make students use just for fun. In, fact Pi can be represented in a formula, such as C/D. What this represents in the circumference of a circle divided by the diameter of a circle. As, I was describing this to my students they were quite surprised. We have a round table in our classroom. I demonstrated how we measured the outside of the table and then measured across the table. We then divided the numbers and viola, we got 3.14. I explained that this will work for any circle they see, it does not matter how big or how small the circle is. When we divide the circumference by the diameter, we will always get PI.
But, as my father in law, who is a former NASA scientist asks me how Pi can be irrational, but the measurements of the circumference, which is a finite number divided by the diameter, which is also a finite number give us an irrational number? I told them that when we measure, we are not 100% accurate. In fact, when we measure, we round off to a point to make it easier to use. We may be rounding off to the 30th place after the decimal, but we are still rounding.