Registration is now open for the Saturday-morning session Science on Saturday, on October 31 at MIT’s Lincoln Laboratory (244 Wood Street in Lexington).   The topic will be Cyber Halloween, for which Bill Streilein will take students through a Cyber House of Horrors — representing online dangers — and teach them how to be safe.  All are encouraged to wear Halloween costumes.  All children (5-17 years) must be escorted by an adult, and every adult must be escorted by a child or children.  Children under 5 are not admitted.  Admission is free but each person attending must be registered.  Space is limited, so register online soon for either Session 1 (9AM to 10:30AM) or Session 2: 10:45AM to 12:15PM).  Adults much bring government photo identification.  See other rules on the registration pages.