Every person learns in a unique way, and a skilled teacher will be able to adapt their communication style so that you can respond most easily. For example an adult learner will require a quite different approach to a child, and with young children, extra patience, understanding and humour are essential to capture a wavering attention span.
The typical music lesson will be of 30 minutes duration. Your teacher will normally use the first part of the lesson listening to what you have practised from the previous lesson, commending your successes (hopefully!), correcting any errors and pointing out areas of musical enhancement or continuity, if there is more of the assigned material to learn. If little or no practice has been done, the teacher will not be able to use this time to the greatest effect.
Next, your teacher may introduce new material, perhaps asking you play it through first, drawing attention to any pitfalls you may encounter. Any remaining minutes at the end of the lesson may be used for something more light-hearted, eg. playing duets perhaps or doing aural exercises.
In order to make significant progress then, there is much to fit into that thirty-minute period, which requires consistent engagement from the student. Whilst the teacher will be able to judge the intensity level to which the student can best respond (and enjoy!), the student must understand that their attention and cooperation are expected throughout. Parents who sit in can assist by helping an easily distracted child stay focussed, but should otherwise not interrupt, saving any questions until the end of the lesson.