Angles and degrees should have their units redefined so that they will be logically simpler and easier to learn. Angles could be redefined so that there would be 100 degrees in a circle, 100 minutes in a degree and 100 seconds in a minute. Maybe a circle could have 200 degrees so that a semicircle would have 100 degrees and a quarter of a semi circle would have a nice, round 25 degrees. In many or even most applications, semicircles have more importance or relevance than do full circles.