Arts Collaborative Medford is hosting its third Jam Down By Riverside, a direct descendent of the now defunct blues jam at the Porch Southern Fare & Juke Joint, which was a descendant of the Johnny D’s blues jam. Presented by the Medford nonprofit Down By Riverside, Inc., the Jam is for building community and building skills. People of all ages, abilities, styles and instruments are welcome to join in the jamming. There is not a strict blues-only jam rule, but probably 85% of the repertoire is blues or blues-derived music. All are invited to play or listen. Organizers are putting out a special call to teachers and their students to participate as they are specifically trying to facilitate connections between people with more experience and those with less experience. This is a potluck event, so bring food to share or bring you own eats. Beverages will be available for purchase. Down By Riverside welcomes donations to offset the cost of the event and to show support for the organization.