One embodiment of the present invention includes an optical cavity, a source to provide light to the optical cavity, a sensor to detect the light and generate a corresponding sensor signal, and a servo device including a feedforward input and a feedback input. The teacher station comprises a computer and a lesson creatorreviser program executable by the computer that can generate a lesson file representing the audio and visual content of a music lesson. If at least one potential artificial algebraic loop exists in the process, an artificial algebraic loop solution manipulates the order or manner by which the functions are executed to eliminate or otherwise resolve the artificial algebraic loop.