Time

Do you need the class to actually end (that is, the professor dismisses the class), or do you just need the scene to end?

If it's the latter, you can have the lights dim in a stage direction, and have the students exit.

I edited my earlier post before I saw your reply.

I think you can still use a stage direction to indicate time.

The professor lectures for the first two pages.

At an appropriate point (say, when the professor is not speaking but writing on the board), the lights dim, and then . . .

Either have the students exit during the fade and then have the professor alone when the lights come back up, or . . .

Have it be the end of class when the lights come back up, then have the professor dismiss the class.

I'm a little rusty on my stagecraft, so I hope I'm close to being right on this.

That is exactly how you want to end it (or at least how I would end it) this is where theatre's suspension of disbelief comes in.

I want to play contrarian here:

You definitely can use a light fade down and back up but it will always look contrived particularly if it happens just a few minutes after the beginning of the scene.

Why do we need to see the beginning of the class? If it is to introduce the professor or student(s), or set some back story, there are better ways of doing it.

Why is the professor remaining after the end of the class? If it is to meet someone, have the new character introduce themselves. Even if the professor knows the new character and they would be on a first name basis, have the new character enter before the last student has left and call the professor by his/her last name.

One of the rules of play writing is to start the play at the last possible moment. What happens in the first part of the scene that the audience ABSOLUTELY has to know that absolutely can't be introduced anywhere else in the play? Introductions and back story can (should?) always be introduced as the action of the play unfolds.

Be creative: Find a way to do it without the light dip.

Just my two cents.

Doug B

You have some good points, Doug. And I don't consider it contrarian to my earlier suggestion. Just maybe a better idea.

Doug is right. Don't do the lights dip thing.

Start the scene after the end of the class - if you have the class you run into a host of problems? How many students are in the class? You really want to have 10 more characters in your play that probably won't be all that important.

You said that the dialogue fits the beginning of the class better - if so, cut it and write something else. It's not set in stone once you've put it down. You're going to write all kinds of things that won't make it into your play, often for the very reason described above - it makes the play clunky.