Celebrate pi - and pie! - on Saturday as the fun begins four minutes early at the Franklin Institute.

In honor of the mathematical constant pi, the institute will open at 9:26 a.m. instead of 9:30. Why? The first eight digits of pi are 3.1415926, so on 3/14/15 it makes sense to open at 9:26. Pi Day will feature a pi station where guests can learn about the number's significance and measure it without doing complicated math. There will be catapult pie launching and plain old pie-eating, plus the presence of Pi Day mascot Pi Man. Those at the door at 9:26 a.m. will be entered in a raffle to win a year of free family membership.

Pi Day, 9:26 a.m. to 4 p.m. Saturday at the Franklin Institute, 222 N. 20th St. General admission of $19.95, $15.95 ages 3 to 11, free for members. Information: 215-448-1200 or www.fi.edu.

Master of balloons

Magician, comedian, and balloon manipulator extraordinaire John Cassidy brings his Balloon Freak Show to Phoenixville's Colonial Theatre at 2 p.m. Saturday.

Experience Cassidy's outrageous balloon tricks, some magic, and a lot of laughs in this interactive show. The Philadelphia native has won Guinness world records for most balloon sculptures completed in one hour (747) and most completed in one minute (13).   

"Balloon Freak" John Cassidy, 2 p.m. Saturday at the Colonial Theatre, 227 Bridge St., Phoenixville. Tickets: $6.50. Purchase online at www.thecolonialtheatre.com. Information: 610-917-1228.

The dark tale of Maleficent

It's Friday the 13th. What better night to catch a free screening of Maleficent, the Disney film about the self-proclaimed Mistress of All Evil? It's at the People's Emergency Center in West Philadelphia at 6:30 p.m.

Maleficent, starring Angelina Jolie as the title character, puts a twist on Disney's classic 1959 Sleeping Beauty. When a neighboring kingdom threatens Maleficent's realm, the queen puts an unbreakable curse on her rival king's newborn daughter, Princess Aurora. But as the years pass . . . nope, no more - you'll have to see it for yourself. Light refreshments will be served. All children must be accompanied by a parent or guardian.

Maleficent screens at 6:30 p.m. Friday at the People's Emergency Center, 325 N. 39th St. Admission is free. Information: 267-777-5800.

mpeters@phillynews.com