The job of a teacher is to teach the children academic and also some life skills that they will need to succeed. Often class sizes are in the late twenties or early thirty’s and so it can be hard for a teacher to be able to spend time one on one with the children on a regular bases.
It is vital that you are able to have control of the classroom at all times to ensure that everyone have the chance to learn what is being taught and that all the pupils remain safe. The children need to be able to respect you and for you to know that if there was a fire for example, they would do as you tell them to and so you can all exit the building safely.
If you have one or two pupils that often are disruptive then you need to make sure that you keep them a part. Children often play up more when they are with other disruptive pupils. You may need to ask your TA to keep an eye on them at time when you cannot to ensure that they are not disrupting other people who are trying to learn and get on with their work.
It is important to take a fair but firm stance and to show the pupils what level of behaviour you expect from them right from the beginning.