Get a large A3-size piece of paper and create two columns; a narrow one containing the names of the children in alphabetical order, and a wider column where you will draw a star next to a child's name who performed well during an activity. Draw a half-star every time children have been quiet to keep the class disciplined. The stars must be drawn with a gold or silver marker that only you can use to avoid mischiefs on behalf of juniors.
Present four toys to the children and set a price for each of them. The price must be on credits that children earn for every success, rather than money. The toys don't have to be expensive, but not too simplistic either; small figurines of popular superheroes like Superman and Captain America will do the job. Set a price, such as 300 credits for each toy. Every success in an activity will give them 20 credits. Every time they are quiet, they will earn 10 credits. The "payment" can be done through an individual card each kid holds, where you will note down and sign each credit transfer.
Take advantage of children's love for sweets and offer them a caramel or jelly every time they show desire to participate and succeed in activities. Make sure the basket is in a safe place so that kids don't eat the sweets arbitrarily; your desk will be a safe choice. When you buy the sweets, make sure they are healthy for kids, and do not offer them in large quantities; three sweets per day must be the most each child can achieve.
Establish a part near the end of the day when you will gather around the television with the children and watch an episode of their favourite cartoons. All kids will enjoy this part, especially when they can choose which cartoon series to watch. This choice should be left to the kid who performed better during the day's activities and did not create any trouble with his or her behavior. To avoid a case of a single child continuously choosing what everyone else will watch, set a limit of two choices per kid per week.