How could I deepen my voice for a school play?
You must always be very careful when attempting to lower the voice, especially when you are young, because the voice is at a very fragile developmental stage. Find other ways to develop and portray the character — through posture, movement and attitude. Then you don’t have to alter the voice as much to be believable in the role. Rather than working alone, work with a voice coach to develop the character’s voice. Moan a little on an “oh” vowel and make sure you can feel the vibrations in your chest. Keeping these vibrations is more important than lowering the pitch at this stage in your life.