Here are some useful resources to practise rhythms. They can be used for piano students or classroom contexts. Try keeping a steady beat with your feet, or for greater complexity, tap the beat with one hand on one knee while keeping the rhythm with the right or left hand.
There are 10 pages ranging from basic to more complex:
Rhythm Worksheet No1 Whole, Half, Quarter, Sixteenth Notes
Rhythm Worksheet No2 ti-tika, tika-ti
Rhythm Worksheet No3 Alternating ti-tika, tika-ti
Rhythm Worksheet No4 Basic Dotted Notes tam-ti, tim-ka, three
Rhythm Worksheet No5 Syncopation Basic
Rhythm Worksheet No6 Syncopation Advanced
Rhythm Worksheet No7 Dotted Notes and Syncopation
Rhythm Worksheet No8 2-Bar Ostinati
Rhythm Worksheet No9 Whole, Half, Quarter note Rests 2-Bar Ostinati
Rhythm Worksheet No10 Quarter and Eighth Note Rests