practice on (someone or something)
To train for some activity by doing drills on someone or something. (Spelled "practise" in British English.) A noun or pronoun can be used between "practice" and "on" to specify the activity one is training for. The doctor asked if the trainees could practice checking blood pressure and heart rate on me. I want to make sure the sculpture turns out how I want it, so I've been practicing on these concrete blocks before I move on to the marble.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
practice (up)on someone or something
to train or drill on someone or something. (In preparation for the real thing. Upon is formal and less commonly used than on.) I do not want a dental student practicing upon me. I want to learn how to braid hair. Can I practice on you?
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs. © 2002 by The McGraw-Hill Companies, Inc.