I taught in Beijing for many years, and had my fair share of noisy, unmotivated students. While HogzTCP is right about the importance of engaging your students through interesting subject matter and delivery, there are some groups of students who, no matter what kind of lesson you have planned, will still be troublesome. Hence my use of scoring and reward systems.
Scoring System - young learners often need to be instantly rewarded for their efforts, as they fail to fully understand the benefits of learning a second language. You award students points throughout the lesson for participation, improvement and - in some cases - good behaviour. Scoring systems enable you to reward positive behaviour as it happens, using very little time, and without constantly relying on time-consuming and costly reward systems.
There are countless scoring systems at your disposal, which usually involve some form of points being drawn on the board, such as stars. For smaller classes, write their names in a list on the board, and draw the points next to them. For larger classes, divide them down the middle and have two teams; when a student from that side of the class earns a point, you draw it under their team.
In reality, you aren’t giving them anything at all when you draw a point on the board. However, if the students know that at the end of the class you will converting these points into a tangible reward, they will be worth a great deal to the students and they will work hard to earn them.
Reward Systems - Your students will soon realise the points you are giving them are worth nothing, so you need to change that. A reward system can be as simple as giving them 1 piece of candy for every 5 points they earned (if scoring them individually), or giving the winning team two pieces and the loosing team one (for team scoring). However there are some more interesting ways to convert the points from the scoring system:
'Group Ascension' - All the well-behaved students in the class will receive a minimum of one lolly at a time prescribed by you. The students can increase the amount of lollies they get by earning more points in your scoring system: the more points they have, the more lollies they get. Group ascension is designed to be used with team scoring, with the students working together as a team to earn more points, but it also works with the class as a whole: simply add all their points together at the end of class. Don't give away too much candy! Add their points up over two or three classes before converting them, and make the conversion rate fair but not too generous! I gave my students on average three Jelly bean sized candies every two weeks. Of course, you need to change the prize to match the age and maturity of your students.
'The Mystery Box' - This is a reward system that every new teacher should consider including in their classes from day one. The Mystery Box is a similar concept to a traditional lucky dip, and can be as simple as a shoebox covered with question marks and filled with small prizes. At the end of class, good students get to write their name on small pieces of paper (usually 1cm x 1cm), which then go into a bag.
The teacher then draws out a few names, and whoever has their name drawn gets to take a prize from the box. By using this reward system from your very first class, you will set yourself apart from their old teacher, and will instantly get your students more motivated to participate throughout your lesson.
You can use this in conjunction with your scoring system. For example, you may decide that 5 points = 1 name in the bag. Again, adapt this to the age and maturity of your class. Don't use this one with more than 20 students, otherwise you will be wasting too much time. Group ascension is a better choice for the larger classes.
Hope this Helps!
Adapted with permission from the You Can Teach TESOL course: You Can Teach TESOL and Recruitment in China : Home