I learned something today too!

In Math Workshop, we've been studying angles and how to measure them.  As I've taught lessons this week, I thought, I wonder why we use 360 as the number of degrees in a whole circle.  It's not a common number.  I was preparing a chart after school today, and while searching for an image of a 360 degree circle, found the answer:

Why 360 degrees? Probably because old calendars (such as the Persian Calendar) used 360 days for a year - when they watched the stars they saw them revolve around the North Star one degree per day.

Also 360 can be divided evenly by 2, 3, 4, 5, 6, 8, 9, 10, 12, 15, 18, 20, 24, 30, 36, 40, 45, 60, 72, 90, 120 and 180, which makes a lot of basic geometry easier.

Just another example that we are all life-long learners!  :-)