I volunteer and teach outdoor ethics (Leave No Trace). I have a legal agreement with the Leave No Trace Center in Boulder, carry their liability insurance, keep first aid and CPR certifications current and have worked with state DNR and scouts for years. I always require that the kids are chaperoned by someone else. Unfortunately, this is the only way you can "volunteer" to help kids. You may want to check in to local scouting opportunities or public classes through local parks departments or with local fishing groups as opposed to private sessions. The local park may be interested in you volunteering.