The 2000 Children's Internet Protection Act (CIPA) determined in Federal law that all schools and public libraries must protect minors from viewing obscene or harmful images when using the Internet. This is a view that many would endorse, and it is now commonplace for schools to block websites in order to protect their students when using the Internet and help them remain focused on their studies. The main argument against blocking websites is demonstrated by the American Library Association's 2003 Supreme Court challenge of the CIPA based on the First Amendment of the U.S. Constitution.


Schools can place websites on a blacklist using an Internet filter; blacklisted sites can no longer be viewed by students. Blacklisting is an exhaustive and on-going process and, while it offers a good level of protection, it can never cover the entire Internet -- some undesirable pages will always get through the blacklists. Furthermore, many students have worked out ways of negating blacklists, such as using Internet proxy websites, which allow them to visit websites of their choosing without being easily detectable.


Whitelists are more prohibitive than blacklists and apply filters in the completely opposite way. Instead of prohibiting students viewing websites, whitelists only allow them to access websites that are whitelisted. As such, educators can be confident that their students are not able to view harmful material on the Internet, but the use of whitelists also means that students may miss out on genuinely useful resources. Moreover, whitelists are also not a 100 percent solution and children are still able to use proxy servers to access undesirable content.


Although it is becoming less common with the prevalence of Internet filters, some schools can elect to simply supervise their students. This approach is aided when all computer monitors face the same direction, so an educator standing at the rear of a classroom can view each screen from one vantage point and take action against any students looking at inappropriate material. Often, schools choose to apply one type of Internet filter and supervise students also.


There are several clear advantages to blocking websites in schools. Firstly, certain parts of the Internet, such as social media websites and chat rooms, are a breeding ground for potentially dangerous child predators. Often students can be naive and overly trusting of people they meet in online communities, revealing personal information and finding themselves in dangerous situations. The use of Internet filters helps fight this phenomenon and protects students in elementary schools. Blocking websites also helps students focus on their work, as they are not distracted by playing games or visiting social networking sites. Furthermore, filters can be used to block out any content that is misleading, unhelpful, too complex or factually incorrect, ensuring students receive consistent and useful information.


While there are clear safety and behavioral benefits to be gained from blocking websites, there are also a few disadvantages. Firstly, students may be denied access to useful resources, and they might find their interest in learning is stifled when they can't search freely around a topic. A secondary issue is that, when Internet filters are applied, educators can be naive and assume that their students are safe while this might not necessarily be the case. Finally, in 2003 there was a Supreme Court challenge against the CIPA using the argument that mandatory use of Internet filters in schools is an infringement on students' rights as protected by the First Amendment.