1. A method for operating an injection valve having a nozzle-needle driven by a piezoelectric actuator, the method comprising: capturing an ACTUAL quantity of a characteristic comprising at least one of the group consisting of: actuator current, actuator charge, and actuator voltage continuously during an injection process; reconstructing a dynamic progression of the nozzle-needle stroke of the injection valve on the basis of a model structure for a motion of the nozzle needle of the injection valve, ascertaining a DESIRED quantity corresponding to the ACTUAL quantity captured, wherein the dynamic progression of the nozzle-needle stroke is reconstructed via a simplified model structure by introduction of at least one discrete measured value pertaining to the injection valve into a basic model of the nozzle-needle motion, the at least one discrete measured value including an internal variable of state chosen from the group consisting of: piezoelectric inertia forces, piezoelectric speeds, needle inertia forces, and needle speeds; comparing the DESIRED quantities with the ACTUAL quantities; and minimizing the difference between the DESIRED quantities and the ACTUAL quantities.