The Cambridge Science Festival is the national leader in its field, with over 160 activities and events spanning 10 days, April 15-24.  You can filter this year’s online schedule of events by age (family/teens/adults) and type (activities, workshops, performances, talks, other), or date — and browse the list of exhibits, recurring programs and tours, and Museum of Science activities.  Register now for those events that require pre-registration or tickets.  The Science Carnival is free and takes place on Saturday, April 16, 12-4PM between Harvard Square and the Cambridge Public Library.  It’s too much to keep in your head.  Use the Guidebook mobile site or the Guidebook app for your mobile guide to events.