It is not idiomatic "to give" a class. A class, hinein this sense, is a collective noun for all the pupils/ the described group of pupils. "Ur class went to the zoo." Let's take your example:One-on-one instruction is always a lesson, never a class: He sometimes stays at the office https://youtu.be/T0zWXvhEQwo?si=wNc6ihu97ShtIl7u