As a teacher you may be required to cover another class from time to time. This may be due to illness or a course. Pupils often like to try and push their luck with a new teacher and will often act up to see how far they can push the boundaries. It is important to teach your new class how you would your own. Be sure to set the rules as soon as you go in and don’t stand for any messing. Always have worksheets at the ready, you may have to cover a class that has now work left for them but even if they have, you can keep your worksheets on standby should some pupils finish early.
The important thing when covering a class is not to panic and show that you are unsure of what you should be doing. If you are covering in a new school then make sure you arrive in plenty of time and find out exactly when assemblies and break times are etc.
If you have a TA working in the classroom with you then they will probably have a good idea of what should be going on and will be able to give you the heads up on any pupils that are normally disruptive that you may have to keep an eye on.