The safety of elementary school pupils on the internet (especially on social networks, such as Facebook, Twitter, Instagram, etc.) is a current and often discussed problem. In previous decades, attackers (e.g. pedophiles) usually lured children with sweets or puppies. It was risky because they had to meet the child in person. Nowadays, attackers can hide themselves behind fake profiles on social networks. In this way, they try to build friendship with the children and gain their trust. Later, the child can be convinced or forced to send his or her intimate photos to the attacker or to meet the attacker in an arranged place. This article deals with the safety of pupils of elementary schools in the Czech Republic on the internet. It outlines basic concepts and describes the most common problems related to this topic (for example cyberstalking, cyber grooming, ...). It also deals with prevention issues in the context of Czech education. In 2016, a survey was carried out at elementary schools in Aš (a town in region of West Bohemia) and in Železná Ruda (a town in Southern Bohemia). This allowed comparisons between the two regions of the Czech Republic. The survey also provided us with information about the behavior of Czech elementary school pupils on the internet
