Girls and Boys, 4-8th grade, are invited to join RHoK Jr at a special one day hackathon at Howard Whittemore Public Library where they will be working with computer science mentors, to create technology for social good by helping local charities.     Android devices will be provided for building and testing apps, but you are welcome to bring your own. Participants may also bring their own laptops to work on.   The program is supported by a grant from the…