Students in this elementary school in the Serbian city of Nis, are not allowed to bring their mobile phones to class.

Principal Dusica Trickovic says the overall grades of students have improved since the new rule was introduced.

"Now, the communication among students has improved, it's more direct. Even the classes are more efficient because there are no interruptions,"  Trickovic said.

But not all students are happy. Some leave their mobile phones at home but others try to use them in secret.

There's no law in Serbia banning phones in schools but in some countries, like France, there are laws to regulate the issue. 

TRT World'sMilivoje Pantovic reports from Serbia.