Engaging your community in STEM education can be as easy as finding others interested in it. You can start with the local library to see about maker fairs, robotics clubs, science clubs, etc. The school science teacher may also know of similar events. Finding other community members who care about quality STEM education is a good way to start community engagement and advocacy.
Another approach is to work with local businesses and leaders who care about STEM skills also. The local Chamber of Commerce is a good place to look for these connections. The Chamber may also be willing to be a partner.
The local school board is another partner to engage, as is the local library. Both have an interest in growing the local community through quality schools and education. They should be natural partners.
US2020 is a particular program in the Indianapolis area which links STEM mentors with interested students. More information is here.
The Million Women Mentors program seeks to identify one million STEM professionals who will commit to mentoring a female student or worker to encourage them to pursue a STEM degree, enter a STEM profession, or stay in a STEM profession. More Information is available here.