Students look at me as if I am an embarrassing parent, but I see that glimmer of a smile as they walk into my room. Today is ‘Pi Day’ and the perfect excuse to celebrate the magic that is Mathematics.

The day begins with a competition in tutor time to see who can recite the most digits of Pi. It never ceases to amaze me how much the students enjoy this challenge, and how well they perform. I have had students recite Pi to up to 50 places after just a few minutes of study. Today, one of my tutor group recited 30 places after about 3 minutes of looking at the numbers on the board. Amazing!

“How many decimal places has someone remembered Pi to?”

“Let’s Google it, shall we?”

The world record is currently held by Rajveer Meena of India who recited Pi to 70,000 decimal places.

“But that must have taken them ages to say all of those numbers out loud.”

Well, if we think about how long it takes to say a number on average, we can use Maths to work it out. (In case you are wondering, it took him 10 hours!)

The celebration of Pi Day today took lots of different forms. My Year 11 classes revised exam questions to do with circles and pie charts. My Year 8 class were given a unique “slice of pi” which consisted of 10 digits of Pi and they had to calculate the mean, median mode and range of their ‘slice’. My Year 13 Core Maths class tackled Fermi Estimation problems such as “How many Bramley Apple Pies could fill this room?” and statistical analyses on the probability of a student recalling more than 10 decimal places of pi based on a sample of attempts which had taken place by students today. The things that really filled me with joy today were the questions and the curiosity about what Pi actually was.

“Does it really go on forever, Miss?”

“But how do they know?”

My favourite question:

“What actually is Pi?”

“Take the diameter of a circle. Pi is the number of times the diameter of a circle fits into its circumference, which is just over 3 times. In fact, that relationship is so unique, that the digits never end. Isn’t that just mind-blowing?!?”

“What, even this tiny circle here?” (student draws a small circle in his book).

The students are interested; they want to know more. This is the whole purpose, the whole beauty of celebrating a day such as this.

Moving onto my Year 10 lesson this afternoon.

“I bought a DVD from Amazon. The review gave it 3.14 stars. Turns out it was pirated”.

“Oh Miss, that’s terrible!”

We had a slightly different task this afternoon, and that was to find out when our next Pi birthday was. In case you are wondering, mine is 22^{nd} May, and I am looking forward to receiving Pi related gifts. Students eagerly calculated how old they were in Pi years after working out how old they were in years and days (bring out the knuckles, January has 31 days, February 28, March 31….) From this, students worked out how long it was until their next Pi birthday (a whole 5 Pi years old!) and translated this back into ‘human’ years. Turns out I share a Pi birthday with two of my students!

The real highlight of this lesson was a rather impromptu visit to the website www.mypiday.com. If you enter a sequence of numbers, for example a birthday, it tells you how far through Pi that sequence of numbers occurs. What fascinated the students the most was that for every student who volunteered their birthday to be entered (they all wanted to know!) that there was a position for that sequence of numbers in Pi. We had a bit of a competition to see whose birthday appeared in Pi first. I was in the lead for a short while at digit 120,533 until one student found their birthday sequence to appear at digit 7,285!

Today we celebrated Pi Day 2017 in lots of different ways across lots of different classes. I hope my students have gone away with Pi on their mind, whether it is a question, a curiosity, or just understanding a little more about what Pi is, or how magical Maths can be. In fact, one class have suggested that 15^{th} March should be known as “Pi Boxing Day”. This sounds like a great idea to me!

Michelle Mahoney, Maths