Casting a show in an educational setting is a difficult process. A lot of different elements go into my casting decisions. A director spends quite a bit of time with a script before the audition process even starts, they have usually read the play four or five times by then. Which means that the characters are very much alive in my head. I can hear their inflections, imagine their facial expressions… in other words I’ve really gotten to know them. Sometimes one actor will come in and they portray a character exactly the way that I imagine them, so that actor gets the part.
Sometimes two or three actors will come in and get it pretty close, so any of those actors might play the role. When that happens I look at who has had a larger role in the past, and who has been a great team player patiently waiting for their turn in the spotlight. I also take into consideration grade level. A 6th grader has a lot more opportunities to get that big part in the future than an 8th grader does.
A big deciding factor can be behavior in past productions. If a student wasn’t memorized when they were supposed to be, if they missed their entrances all of the time, if they missed rehearsals or talked during instructions… it might be that they aren’t ready for the responsibility of a big role yet.
And finally, actors don’t get up on stage in a bubble. They have to relate to other actors and connect with them onstage. Sometimes two actors are able to get onstage and act as if they’ve known each other for five years instead of five minutes, and if a show needs that chemistry on stage, then those actors are going to get the roles.
So. Focus on the things you can control. Don't talk during other people's auditions. Research your character and the play. Read everything the director has shared about auditions and the show. Be loud on stage. Be polite. Make big character choices for your audition, and try to connect with anyone you share the stage with.
Oh, and if you can, have fun.
Break a leg everyone. I'm rooting for you.