Lesson 2 Quarter and Half Notes

The second lesson of the book Alfred's Self-Teaching Adult Piano Course  introduces the length of time a note is held.  In particular, it introduces the quarter note.  It suggests that the basic time unit is the measure, and a measure contains four beats.  A quarter note gets one of these beats, thus, a quarter of a measure.  I know that's not all there is to say on timing, but for now, I'll leave it at that.