Sister doesn't give star ratings. It would probably be against some heavenly code of ethics. She does, however, have plenty to say about the movies, where lapsed Catholics presumably are getting their spiritual guidance these days.

Such is the premise for Vicki Quade's latest one-woman, Catholic-themed play, "Sunday School Cinema," which just opened at the Royal George Theatre.

Sister (an ebullient Elaine Carlson), a nun with a habit of showing up in other Quade productions ("Late Nite Catechism" and "Put the Nuns in Charge"), engages the audience from the get-go in this highly interactive show. Ruler in hand, she scolds any latecomers, asks folks what movies they've seen lately -- which will keep the show fresh from week to week -- and even gives a homework assignment to be done during intermission.

"The Song of Bernadette," that 1943 tearjerker about a peasant girl whose miraculous vision of a woman in white sends her little French town into a tailspin, is Sister's favorite movie (go figure), and her enthusiastic lecture -- complete with an audience-assisted re-enactment -- will make you want to queue it up on your Netflix account. And to hammer home the point of just how good a movie it is, Sister tells us that the woman who played Bernadette -- Jennifer Jones, who went on to win the Oscar -- was "really acting," because in reality "she was a divorced Protestant!"

The partly scripted/partly improvisational lecture continues to evolve in funny and unexpected ways. Sister's riff on leprosy in the movies as it relates to actress Jean Simmons is a crackup. And then she tries to make a correlation between St. Michael the Archangel and Samuel L. Jackson's character in "Snakes on a Plane."

In the second act, Sister divulges a surefire formula to determine if deceased actors have gone to heaven or hell (it involves math, so you might want to pay attention) and then leads a group sing-along.

The audience participation as well as the actor's ability to remain on her toes is what makes or breaks a show like "Sunday School Cinema." Carlson, who does her part with her quick wit, has an obvious comfort with the character. So, the rest is up to us; just as with Sunday mass, you get out of it what you put in.

And if you're particularly attentive, you might walk away with a St. Christopher medal or a glow-in-the-dark rosary.

Note: Also in open run at the Royal George are "Late Nite Catechism," 8 p.m. Thursdays and Saturdays, and "Put the Nuns in Charge," 8 p.m. Fridays and 5 p.m. Saturdays.