Getting students' attention
Getting students' attention is a key part of teaching a group, as explanations, instructions and demonstrations will invariably have to be repeated if students are not paying attention when the teacher is talking. It can be especially hard with large classes and groups of younger learners, yet there are various techniques which can be employed to overcome these difficulties. Some techniques are as follows:
Ironically, doing very little sometimes works very well; simply stand by the board, let your eye roam over the class and wait for them to notice that you have something to say. Remember not to start speaking until the whole class is quiet!
Although a little extreme or shocking, this technique works in that it marks a change from using your voice to get attention, and will therefore (theoretically) be effective. All you have to do is create a sudden loud noise such as a whistle, or a quieter repetitive noise such as by tapping the board. This tactic will work just fine, but may be best reserved to times when a class is being unusually rowdy.
Mimic the teacher
Similar to a classic drinking game without the alcohol, this tactic can be used in class to comic effect but is best reserved for younger learners. Stand in front of the class and strike an unusual pose such as with both hands on your head, pulling a funny face, standing on one leg, doing an army salute, etc. Don't say anything but do look at the students to make it clear you are asking for their attention. The last student to mimic you (and stop talking!) is the loser.
This technique works to gradually draw students' attention towards the end of a speaking activity, and it works well with small groups. When you think a task should end shortly, simply go up to a pair of students who seem to have finished and have a quiet chat with them about anything - just smalltalk as you might before a lesson begins. Owing to the tendency to eavesdrop, the rest of the class should begin to listen in and eventually everyone will be paying attention.