This was some years back when DD was in elementary but the school had after-school Mad Science sessions (in blocks of maybe six lessons or so, can't recall) and she really enjoyed them.
They also used some parent volunteers (not to run things but mostly to have some adults around -- it allowed for more kids to participate and the adults could help with hands-on stuff). I did that several times and thought it was a good and engaging program, and I enjoyed the volunteering too. Consider asking if you can help out, if you want to see how it's run.
These are usually only a few sessions at a time so sign up for one set of sessions; it's not like it's a commitment for the entire school year. Let your kid get a taste of it.