For those of you who do not know anything about pi (are there people out there who do not?), pi is an irrational number (thus it is a never-ending decimal and cannot be written as a fraction accurately) that is used in math. It is one of the most well known irrational numbers and has been given the name pi after the Greek letter. It is approximated to be 3.14 or 22/7. These are usually all right approximations for most school age kids. However, you can find further approximations on your calculator or computer (see below).
There are many different things you can do to celebrate Pi Day. Of course my favorite (and most math teachers' favorite) involves pie. Yes, it is the one day we can actually have a party and justify in the math department. Always a bonus. Hazel and I will be making apple pie on Wednesday assuming we have time. I have to work out the schedule of Wednesday with Steve since he is off so we can do a grades tour at Hazel's school and we are sending Hazel to my mother-in-law's for the morning. If not we will be making pie on Tuesday and eat it on Wednesday. And or course it has to be apple pie since that is Steve's favorite dessert.
However for those of you who like to do some lessons with your children or have older children, I will provide you a few more activities. There is great reference to the number pi in history including in the Bible. There are also many different cultures that had approximations of pi in ancient times. There are several sites that have history of pi. Here are a few I found doing a google search: exploratorium ualr Math 4 All Think Quest. Those will at least provide you with a history of pi over the last 4000 years.
You can also find in this computer age pi calculated out to 1 million decimal places. I know some people have their students memorize pie to 100 decimal places. I'm not sure why and cannot see any reason to do this, but is an activity if you want to torture your child.
The number pi is quite simple to see how they discovered it and leads to an easy lesson for you to do with children. Your child will need to know how to divide or you will need to help them with a calculator. All you need to do is measure different circular objects. You need to measure the circumference (distance around the object) and the diameter (distance across the circle through center). pi is the circumference divided by the diameter.
Here is a Word document to do this including an additional question of plotting your answers to see the ratio.
You can also find pi by "squaring the circle". To do this you will need the vocabulary illustrated in the picture above. The radius, apothem and side length can be found in any regular polygon. As you find the area of a regular polygon with radius of one, the more sides you add the closer to pi you will get.
Here is a link to a Word document for this activity. If you are working with a child who knows right triangle trigonometry here is a Word document with less information given.
And of course a final activity that you can do is pie charts or circle graphs. This will include reading pie charts, creating pie charts (thus knowing how to measure in degrees and knowing a circle is 360 degrees) and then doing a survey to create a pie chart. Here is a Word document to do this.
If you try any of these activities I would love to hear about it.