Always remember that kids have a very short attention span, so the ballet routines you put together for them need to be two minutes or less. Try to structure the class in a similar way each week, starting off with a warm-up, then moving on to the routines and finishing with a good stretch. Allow at least 20 minutes in every class for a set of a few short routines that you keep repeating with the children. Make sure you correct their posture throughout the class and focus on the children understanding how they should carry their bodies when dancing ballet.
Give them a few short and fast sets of moves to repeat again and again and notice how much more comfortable children get when they stop feeling stressed and they know what to expect. Make the routines enjoyable and try not to single out any of the kids when they perform the moves, rather have them repeat the short choreographies as a group so they feel more relaxed and express themselves more effectively. Adding props such as scarves and feathers can make the routines more entertaining for the preschoolers.
Children learn and develop their skills by copying others, so use this when you are teaching preschoolers ballet. Ask them to dance impersonating a certain animal, for example a cat or a swan. Ask them to move as if they were princesses, astronauts or swimmers. Split them in small groups of two and have them improvise together with their friend so that they don't feel pressured. Then have them all gather in a circle and dance in character all together while carefully listening to the music and adapting to the rhythm.
Music is crucial when teaching ballet, and fun children's music can make the class more enjoyable for the kids. Mix different kinds, from simple children's songs to short classical piano pieces, but always keep them upbeat so that the kids stay motivated and energized. Singing along with the music -- even when it has no lyrics -- can help preschoolers memorize instructions more efficiently. For example, ask them to sing the dance movements like "Open them, shut them, clap my hands." Like a little poem accompanying the song, the routine will become a part of it, helping the children to stay in rhythm.
At the end of every class, make sure you reward the children by complimenting them on their dancing or by stressing how much they are constantly improving. Give small prizes like stickers, flowers or candy. Tell them that from now on you will be moving onto more difficult routines, since they are doing so well. Arrange little shows for the other students and teachers or for the kids' families and give them a chance to show off their ballet choreographies. Make sure the children feel like their efforts are being appreciated and rewarded, as this will push them to try harder.