National Pi Day is 3.14
Have some fun learning about Pi.
Just cut some circles out of paper, and then have your students use some more yarn to measure the circumference of each of the circles. List these measurements on a chart. Now measure the diameter of each of the circles and then confirm by measuring each of the circles' radii. Show your students how to write the fraction of c/d for each circle and write this on your chart as well. Then have your students figure roughly what the fraction equals and they should quickly see a pattern emerging that the circumference was always a little more than three times longer than the diameter. Now you can give them the name for this ratio, Pi and show them its symbol. You can also tell them that the exact ratio, had your measurements been precise would always be 3.146.
More fun with geometry and circles here.
And then, just for fun, you can make a pie together!