An operation checking unit for a dialysis apparatus (such as a hemodialysis or peritoneal dialysis machine) is disclosed which comprises an identification unit which is configured to detect a user identity of a user. The operation checking unit also comprises a sensor unit which is configured to detect an operating action of the identified user as an ACTUAL-operation data set, and a processing unit which is configured to compare the detected ACTUAL-operation data set with a DESIRED-operation data set stored in a memory in order to generate a user-specific message in the event of a discrepancy.