I don't put too much credence in dream dictionaries or interpretations, mainly because mine do not make a lot of sense and I still believe that each person is unique in how they think and see the world. However, this common theme is difficult to ignore.
Dreams set at school are very often reported by people from all age groups. Sometimes these dreams highlight childhood insecurities that have still not been resolved. For example, this dream, set in a decaying school building, suggests that the dreamer is carrying disappointed childhood expectations or unpleasant memories. In addition, the schoolteacher is a classic symbol for authority and may represent his father and others who have determined the course of his life. Schoolteachers may also represent the censoring aspect of his personality that keeps the chaotic impulses in control. Being scolded may indicate that the dreamer has feelings of guilt, inferiority or worries that his misdeeds will be found out. Alternatively, if the teacher in the dream were praising Gary then it would indicate that he has self-confidence and believes in his own abilities.
Another interpretation of dreams set at school is as a metaphor for what you are learning from life over a long period. These dreams may also carry a feeling of nostalgia and reveal a hidden desire to recapture the freedom, optimism and ambition of these formative years.
At least I'm not dreaming about missing teeth anymore.