Teaching rhythm has certainly been done for forever and obviously still is.  However, what seems to have been missing in doing so for forever is a system or method for processing and understanding rhythms.  With these books, you get that!  

Mr. Dan Leonard, through his years of teaching, developed a system of Counting, Clapping, and Tapping Your Foot that enables students to understand the duration of notes as well as learn how to sub-divide more complex rhythms. The exercises included have been written masterfully; combining tradition and a more innovative approach whereas things are not written as you would typically see them.

These things together make the student have to think and depend on his or herself.  

It is an intuitive method that uses a brick-by-brick approach that gives the music student confidence in discerning simple as well as more complex rhythms.