Last year we activated a number of parks while staying with my Springfield, MO, contingent of kids. The Girl and I drove out to activate the Blue Slip Tower Site, US-11225, during our stay. This is one of the newly added state conservation areas. These are small plots acquired by the state and used by citizens for a variety of outdoor activities.
They are always fun to activate. There is usually an opportunity to get in at least a short hike as well.