In advance, make up a list of about fifty brief bits of dialogue that could be used to start improvised scenes. Write each on an index card and keep them in a 3X5 index card box—so they can be used over and over (see below).
On the day you introduce this begin by seeing what your students know about improvisation. Possibly ask students what the word "improvisation" means, what they think improvisation in theatre is and why improv is important to theatre. ("Raiders of the Lost Ark"--the scene where Indiana shoots the guy with the whip was improvised. pulls his gun on swordsman in city.)
Then discuss the Do's:
-Take cues from scene partner.
-Be spontaneous.
-Make partner look good.
Next discuss the Don'ts:
-Don’t negate. Always answer yes.
-Don’t be a ham. This is a dialogue, not a monologue. Don't ignore/deny scene partner.
-Don’t change the story line. Always use what you are given on the card. You are not to plot the story in advance.
-Don’t respond with a question (acting is doing, not telling).
Now demonstrate the Don’ts. Select one student who reads a card to you and you negate. The students will immediately see that the story goes nowhere. If you need to demonstrate the Do’s, then select another student and proceed.
Now depending on the class and your time frame, you can go around the room and have every student either read a card or react so everyone gets a chance to “play”. Then explain to them that starting tomorrow when the bell rings, one student (you decide where to start in the class, usually based on the seating chart) will pick a card and the one seated next will react. They are to keep the scene going for two minutes allowing you to take roll and get ready for the rest of the class period.
After several weeks, add a new element. Set up a simple playing area in the front of your room. Put two chairs side by side in the playing area. The first actor will sit in a chair and perform some activity in pantomime. The second actor will enter and start the improvisation by using one of the short openers.
Here are some good examples:
Go away.
Gimme.
It's dark in here.
You're sick.
Boo.
Pssst.
Leave me alone.
I'm sorry.
Wake up, dear.
Hold my hand.
Shhh.
There, there-stop crying.
I'm scared.
Today's my birthday.
I hate your guts.
Knock, knock.
You're late.
This is for you.
Drink it.
Don't forget.
I'm lost.
I'm blind.
Catch.
Seven dollars.
Close your eyes.
I beg your pardon.
Answer the door.
There's something in my eye.
Tomorrow.
Here's a dime.
To be or not to be.
It's empty.
My stomach hurts.
There's a bug on you.