The teachers get to be scientists and do research. They have guest speakers. The School of Education evaluated the program. It breaks the isolation of teachers. It's hard to cover all the material of interest and still have time for the teachers to develop lesson plans.
Evening classes are good but the time commitment and scheduling are difficult.
Work both ends toward the middle. Students think science is the most difficult subject. There's a dichotomy between research astronomers and planetaria - neither has been terribly interested in the other. They may have a variety of goals, and may not share yours. If they don't have the background, start with what they do have, and work from there.