How about Woodie's concept of an organic growth of FRC teams from the "bottom" up? He says to imagine a triangle with FLL at the base, FTC in the middle and FRC at the top. (I will add VEX to the middle - I will not speak to his opinion of this - but we are using VEX for 7-12th graders.)
I can say for an absolute fact from my personal experience in 8 years of mentoring/ coaching/ supporting FLL, FVC, FTC, FRC and now VRC teams that the students who are most engaged, productive, rewarding and rewarded are the ones who start robotics activities BEFORE high school.
I also believe it is these "organically-grown" students who keep me personally doing this in spite of every sane reason to quit. Instead of wondering how to get and keep mentors, we need to reach and inspire students who encourage us to go on year after year. Every time I am so discouraged and overwhelmed I get a message or call from one of these kids with a question or message. "Miss Meredith, Miss Meredith!" in an excited (or sometimes pretty hysterical) voice is the one thing I cannot seem to walk away from
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