It is interesting doing a first lesson with an untrained 1- or 2-year-old dog. They are often impulsive and have no clue what you are trying to communicate.
At first, during that first skill exercise, they are somewhat bewildered. I typically start with a problem solving exercise which makes the dog figure out a simple goal with the owner. These dogs are so used to being passive recipients of owner demands, it is hard on their brains to accomplish this first small challenge. They typically fall asleep hard afterwards. Brain work is tiring!
Rescued dogs benefit from these types of exercises. It settles them in ways that are hard to describe. An example is a reduction in attention demanding barking since they are finding other ways to work with their new owners.
I have mentioned this before, but I don’t think a dog should be trained to be a slave. It is better to create a cooperative bond.
Dogs are social, intelligent, trainable mammals.
Plan accordingly.