A few words about improvisation. Drama Books and websites to look at!
"During an improvisation, the actor is forced to react spontaneously to what is happening on stage. All his or her concentration is directed toward the situation and the other actors in the scene. Since no script has been read, the actor has no preconceived way to play the scene. Nothing that happens in an improvisation is planned very far in advance, so the scene naturally has the same freshness and vigor as a moment of real life. If strong enough conflicts are suggested, the improvisation will maintain a good level of intensity. With enough practice, the actor gradually begins to realize that every performance of a staged play must be performed with the same level of energy as an improvisation."
From Improvisations in Creative Drama by Betty Keller
Below are some excellent websites and wonderful texts on improvisation.
This book of games on team-building contains over 40 improv games for developing group chemistry. It helps heighten awareness, break the ice and increase concentration.
This book is a complete improvisational curriculum program divided into workshops. Each workshop contains exercises designed to help students focus on one aspect of a character's personality.
The 900 improvisation ideas in this book provide material that will last for years. It includes character conflicts, solo improvisations, lines of dialogue and reactions to environment.