The following link argue about positive and negative effect of internet. As, in the past 20 years, Internet usage among children has steadily increased Such as Physical Health, Cognitive Development, Depression and Isolation, Social Maladaptation. Therefore, The Internet's wealth of information can add to the child's store of knowledge, provided that the child has learned to discriminate between good and bad information sources. 

 http://www.livestrong.com/article/516549-physical-and-social-effects-of-internet-use-in-children/