Live presentations, the Charles Hayden Planetarium, lightning shows in the Theater of Electricity, and dedicated school-vacation programming in December and February.
Details change often — check with the program.
Museum of Science is listed in the GOkidOZ guide to museum classes and family tours across Massachusetts. Class schedules, free hours and vacation-week programmes change term by term — check the official site above for current listings, and see what else is on during winter break.