In one of her more dour turns on-screen, Meryl Streep plays Sister Aloysius Beauvier in Doubt. Recently, ReelzChannel sat down with the award-winning actress to talk about playing the confrontational nun in the movie adaptation of John Patrick Shanley's Pulitzer-Prize winning play.

RC: Doubt is enough to make you glad to have not gone to Catholic school, to have not had a Sister Aloysius to deal with.

Streep: Yeah, I didn't go to Catholic school but I had a tough teacher -- a tough math teacher and, you know, weirdly it was in eighth grade. I remember everything that guy taught me. I really do.

RC: The tough ones you learn from.

Streep: It's amazing. Fear focuses the mind.

RC: Sister Aloysius is a such a tense character. While shooting The Devil Wears Prada, you kind of separated yourself from the cast, didn't want to be completely friendly. Was it the same kind of experience with Doubt?

Streep: I separated myself in Prada because I didn't want to have fun. They were all having a lot of fun -- Emily Blunt and Stanley Tucci -- and they were a little coterie of laughs.

RC: It wasn't much fun to Miranda?

Streep: I don't think she thought of the world that way. She took pride in her work. I don't know how much pleasure there was. [In Doubt], nobody was having fun, so we were in all the same world. We shot in a very condensed amount of time. There wasn't gobs of sitting around the trailer. We were working...or moving to the next set up. It was a very intense kind of thing. You didn't have to work to keep your fear up, your energy up, or your anxiety. It was all kind of built into the process.

RC: With Philip Seymour Hoffman, when you're shooting and in the moment, did you find yourself saying new things, things that popped up in your head, that Sister Aloysius would say? Did you stray from script? Or is it as scripted?

Streep: It's as scripted. I think I added one thing that John kept in the movie. But no, it's absolutely as scripted. The whole piece doesn't have a lot of room for improvisation because it's so beautifully reasoned and constructed. It is sort of like a thriller, in a way, and the twists and turns are really carefully wrought. We didn't need to embellish.

RC: It's hard to imagine anyone else playing this character. Has there ever been a role that got away from you -- for scheduling or whatever reason -- that you look back and wish you could have done?

Streep: Yeah, but I probably wouldn't have been as good as the person that did it.

RC: Are you going to elaborate?

Streep: I've always loved Patsy Kline and I always wanted to do that story of her life. Jessica Lange did it and she was fantastic.

RC: You got your chance at singing, though, in Mamma Mia!?

Streep: Yeah, I got my chance 20 years later.