A free screening of a short film about the Tucker Elementary School in Milton will be held Wednesday at 7 p.m. at the Milton Public Library. The film was produced by Milton blogger Frank Schroth of MyTownMatters and directed by Michael Lynch. Schroth said he was interested in doing a film about the school after hearing a report from the principal about students’ progress on the annual Massachusetts Comprehensive Assessment System tests. Students at the school were shown the film earlier this month.