Mobile phones, mobile phone base stations, cordless phones and power lines are among the main sources of our daily exposures to radiofrequency electromagnetic fields (RF-EMF). Today, a large proportion of children aged eight and under has used smart phones and tablets for media activities such as playing online games, watching videos or using different applications. Over the past several years, our society has witnessed a rapid growth both in the percent of children who regularly use smart phones and tablets and the time spent using these devices. Expanded access of children to these mobile devices and the games that make mobile phones attractive to young users are believed to be the key factors that increased the time spent by children for using mobile devices. In IR Iran, students are not allowed to use mobile phones in schools. On the other hand, although students do not have access to Wi-Fi in schools, as Wi-Fi provides efficient access to the Internet on the campus, Wi-Fi routers are widely used. The rapid growth of mobile phone use has raised global public concerns especially for children. Focusing on the issue of cognitive performance, this paper is aimed at answering the following question; Should parents let their children use smart phones and tablets?