Rhythms and Beyond by Timothy Loest and Timothy Wimer
From the publisher:
Rhythms and Beyond was written to help students understand fundamental rhythmic concepts while mastering important counting skills. Through 21 sequential lessons, students learn how rhythms are constructed, counted, and played. Most importantly, they discover how to read and perform notated rhythms at sight. Concepts covered include: identifying the exact count where each note is sounded, eighth-note subdivision, syncopation, sixteenth notes, and more.