[Svyatogor]

Hi , according to my experience , something you can do is to make that messy boy to participate more in your class , use him for examples , I mean , imagine this situation :
You are teaching the seasons, choose four students, one represents winter, another one represents autumn or fall , etc , and make this misbehaving guy to be the sun and to pass around the seasons.
This always works , because if you keep the messy students active , they won’t be distracting their classmates and usually they get very focused on what they have to do (if you use them for explanations) because they’re in front of the class.
As the rest of the users say , classes must be fun and challenging, choose an interesting topic, something new or something that happened lately , make them to present news in front of the class , I think something important and useful , is to allow them to choose what they want to do (according to contents obviously), give them the right to decide how they are going to work , and be sure their attitude at activities and classes , will improve.

Hope this is a little of help for you.

Regards.