To be fair, many youngsters are taught that acting merely involves a) remembering your lines in the correct order and b) saying them loudly enough for everybody to hear.

They've learned that the kids who do those two things get the most favor from children's directors.

Unfortunately, some actors never grow out of this phase.

I believe the best solution to this problem is to teach them some improvisation.  I've taught improvisation for the past seven years now and my students are from all ages and acting experiences.

My favorite excercises for teaching "stage presence" (in this case, using the body and face more) make use of gibberish. 

Gibberish is nonsense language that the actor makes up.  It can be any simple sounds -- even just "blah-blah-blah" -- or it can be complex like old-time TV Sid Caeser's famous made-up French, Italian or German (or like "The Muppet Show"'s Swedish Chef who spoke nonsense that only SOUNDED like Swedish).

By taking away their use of actual spoken words, the actors are FORCED to rely on facial expression, body language and gestures.

Here are three exercises I've used:

1) "Gibberish Pitch"  An actor is told he or she is the host of a late-night info-mercial and must sell us (the audience) a product (ANY product) that they ACTUALLY use, enjoy and want us to rush out and buy.  However, they cannot use any recognizable spoken words and must rely on facial expression and gestures to a) help us figure out WHAT the product they're selling is, b) what is so SPECIAL or DIFFERENT about this product and c) WHY we should purchase it -- how will it affect or improve our lives?

After the student performs the exercise (usally less than a minute or two) I ask questions of the audience to try to have the others guess as to what the Pitchman's intentions were.  If there is confusion or disagreement among the viewers, I have the actor repeat the exercise (not necessarily the whole thing) to clarify the points missed until everybody is satisfied.  (This encourages the student not to "cop out" and really commit to trying to get their message across.)

I've had students try to sell non-stick frying pans, hair-care products, energy drinks, vegetable choppers or anything they choose (secretly -- as that is part of the challenge).  One student did a very impassioned and persuasive pitch for instant mac-and-cheese.  And, of course, there's ALWAYS one joker who tries to sell Viagra!  (That's why I insist it must be product they ACTUALLY use and not something absurd or made-up.)

The goal of the exercise is to teach the actor than a surprising amount of information -- even detailed information -- can be relayed without relying on language.

2) "Translator"  Three chairs are placed on stage (or the playing area).  Two chairs face each other and the third is between them, slightly upstage, facing the audience.

Two "Gibbers" sit in the facing chairs and are given a topic or real-life situation to discuss or debate (ie:  Applying for a job; asking for a raise; a parent-teacher conference, etc)  Sitting in the upstage chair between them is the "Translator" who speaks English and must make sense of what they are saying to each other and the audience.  Each Gibber speaks in turn and the Translator relates their message to the other.

The goal of this exercise is for the Gibbers to try to get their message, their needs or their point-of-view by being as expressive facially or gesturally as possible.  The goal of the Translator is to try to figure out what they're saying and relay the messages as ACCURATELY as possible (not as CLEVERLY as possible, which is the temptation).  Even if the intent is clear to the audience or the other Gibber, the two contestants must abide by the translation provided. The exercise continues until the Director stops it or until the conflict is resolved or the conversation reaches a resolution.

3) "Orangutan"  One player is chosen to be the "Human" and the other is chosen to be an "Orangutan" (argueably the most intelligent of the ape species).  They are then placed in a location that one would not typically find an Orangutan (ie: a fancy restaurant, a supermarket, a hospital operating room, the cockpit of a jet airliner, etc).  It is important to remember two things -- a) the "human" is NOT the orangutan's master or owner -- the two must relate to each other as friends, colleagues or equals. and b) the location must be someplace public that would not typically house an orangutan (ie: NOT the zoo, the circus, a pet store, etc.) 

The Orangutan cannot speak English and must convey to the Human its wants, needs, and desires so that the Human can help perform their tasks.  It is up to the Orangutan to be as demonstrative as possible to make the human understand and for the Human to try to keep the orangutan from making a mess of things.

Everybody should get the chance to play an orangutan or the human at least once.

I've noticed this exercise accomplishes several things:  1) it really encourages performers who play the orangutan to loosen up and let fly with lots of body gestures, grunts, screams and wild behaviors (somehow the orangutan is ALWAYS naughty: eating things it shouldn't, climbing on furniture, throwing stuff, etc).  2) it places the actors in an absurd situation that they must deal with truthfully (like an orangutan would REALLY be the nurse in an operating room) and 3) the Human is forced to take an active role in the scene, understanding and taking charge of the situation, not just stand there and say lines. (NOTE:  He must NEVER hit or strike the orangutan, no matter how out-of-hand the beast becomes). 

These three exercises are great fun and are often remembered by my students as their favorites among the class.  I hope you can get some use out of them as well.

Good luck!

Ok maybe I'm not understanding and maybe I'm just boorish and call me Simon Cowel, but how did these seemingly no talent kids get cast in the first place?  Seems that they didn't even display any potential in their auditions.

That having been said it's no surprise that I'm not a fan of the improvisation track as has been suggested.   What you need to do with the talent level you have is actually show them what you want.  Under normal circumstances this is the worst possible thing you could do for an actor.   But these are not normal circumstances and frankly I don't think you have the time to hope that these kids will suddenly blossom.

Oh I can hear the comments now!

Ok I get that but does the theater part of the equation matter less than the youth part?  It should at least be entertianing to the audience and not want to make them run screaming from the room. 

Having been the "victim" of my daughter's middle school drama club where the only goal seems to have been to get them to memorize their lines, it sets me off when I hear things like "they're only kids." 

An audience deserves to get what it pays for.

But then again I'm hard to please.  I also equate the efforts of little "lost" three year olds at my daughter's dance recitals with nails being dragged accross a blackboard.   

Don't get me wrong I'm also my own worst critic when it comes to performing or directing. 

One of the most appropriate sayings that has been pounded into my head over and over is that "Acting is Reacting".  Reminding the actors that might help.  Pointing out that they are always reacting to something in the show might help them focus when the spotlight isn't directly on them.