Ideas and Resources for Pi Day (March 14^th)

Measuring circles of any size has to be done at some time during the day! Calculate Circumference divided by Diameter for each circle and see how close to Pi your answers are. Older students could discuss reasons for the discrepancies. With younger students it is sometimes a good idea for the teacher to “measure” one of either C or D (“in order to make it nice and accurate”) – using the children’s value of their measurement the teacher quickly calculates what the other measurement should be, and everyone is delighted to see that the value for Pi comes out to be a very satisfactory 3.14 !!

This works well as a People Maths activity with a large circle of pupils. Good photo opportunity too if you want to get the local press involved.

Buffon’s Needle Experiment

Buffon’s original experiment dropped needles of length l onto a flat ruled surface with the parallel lines a distance l apart. Buffon determined that the probablity of a needle crossing a line was 2/Pi so by finding the proportion of needles which actually do cross the line we have a way to estimate Pi.

In a class version of this experiment, one could use safety matches, toothpicks or straws, or else Think Big with postal tubes, bamboo canes, lengths of dowel or even frozen sausages!

The Coloured Pi Code

Everyone loves to make paper chains, and not just at Christmas! All you need is ten colours of paper (sugar paper is fine) and either Pritt Stick, Sellotape or a stapler. Your local print shop will quickly cut the paper to uniform size using their powerful machine guillotine, for a small fee. Width : Length should be about 1 : 6, so on A4 paper this corresponds to 9 strips on a sheet (33mm x 210mm). If you are cutting the A4 paper yourself, it is easier to make 8 strips by repeated halving.

Define a colour scheme e.g. White = 0, Blue = 1 etc. and get every student making loops singly until you have about twenty of each colour/digit. Now you have two choice for assembly: staple loops together back to back or link loops into a chain. Once more you have two choices regarding the manufacture of the chain. The first is to use non-descript paper (Maths paper?) to join successive digits in the right order. The other (preferable) approach is to use appropriately coloured strips to link the pre-made loops together. So to make the sequence 1415926 you would use a 4-strip to link the first 1-loop to the second 1-loop, a 5-strip to link the second 1-loop to the 9-loop, a 2-strip to join the 9-loop to the 6-loop and so on. The advantage of using pre-made loops in this way is that the assembly is much, much quicker.

During assembly, it is good to appoint one person to read out the digits and at least one other to check the assembly sequence. Different teams can assemble sections of 100 digits so that these can be linked together to make the final chain. You may wish to put markers / flags along the chain to indicate every 100^th digit.

Head the chain up with either a giant “3.” or Pi symbol and snake it around the school!

Eat a Pie

Any pie would be good, but watch out for those food allergies. As for cutting them up, it would be wonderful to cut pieces of One Radian sector angle, which conveniently gives you six pieces, allowing for crumbs!

Ideas and Resources for Pi Day (March 14th)

Pi History

Pi Legends – People Calculating Pi to Billions of Places:

Websites celebrating Pi

Pi Day Sites

Digit Downloads and Pi Printouts

Songs and Videos

A Pi-em

Pi Day Activities In The Classroom

Giant Circle

Buffon’s Needle Experiment

The Coloured Pi Code

Eat a Pie

Ideas and Resources for Pi Day (March 14^th)