I know a lot of inexperienced YL teachers panic about 'losing control'...a class out of control is a nightmare, to be sure. The key I find is to know what you are trying to do and have a number of options handy; plan A might not be suitable if the children arrive tired or hyper; plan B might not work because the cheerleader in the group is absent or 'the monster' is on form; plan C might not work due to missing CD or xyz malfunction. Whatever. The children will give you a break if you give them a break! If they can laugh with you and about themselves, then you can be the focal point of mayhem rather than one of them, which gives you time for transitions/finding the CD track, flashcards etc. Involve them in your problem eg "Where's my book?"
Compare that with "Sit down. Next we are going to talk about animals. This is a cat. Repeat. This is a cat. Do you like cats? Yes I do. You say that. Yes I do. What's this....."
Another thing children love to do is test the teacher (linguistically, rather than emotionally!). Using numbers is important, but one of the easier things for learners to pick up I think. The question bit is what they need to use just as much! Gang up on the teacher? Even better! After they have exhausted a picture with each other asking eg "How many.......s?" and you are happy with the monitoring you have done gently - challenge the teacher. Make a big deal of being confident, and get the answers wrong :) This will generate plenty of student talk ha ha!
What games do you like to play with numbers? Love to hear about them!