Piano is just like eating, you need coordination. So, practice with a knife and a fork.I had my very first piano student yesterday. Yup, I had my very first experience as a piano teacher with a 'utterly unknowledgable in piano' student, namely Aaron Chan, who suddenly sprouted an interest to go from guitar to piano just because he heard a couple of nice instrumental piano solos.
Step 1: Ask your student to draw a piano or a grand piano will do too. Yup, including the chair.
Step 2: Ask your student to practice drawing the keyboard, over and over again until he remembers the position of the white keys and black keys.
Step 3: Ask your student to label the black and white keys on the keyboard. While he is in the process, please try your very best to act professional and not burst into fits of laughter. It's not nice to laugh.
Step 4: Correct your student's confusion. After so, he has just graduated your class of, "Basic Piano Knowledge for Dummies". You can abort the part of presenting him with a certificate.