Internet Concerns

Hello again.  As I continue on my technological journey, I am at the point where I am pondering what my true concerns are when it comes to using the Internet in my classroom.  I guess I have that worry that all teachers probably have that when students are researching or something along those lines, they will accidently come across something inappropriate.    I would hate to have to explain to a parent or principal how something like this happened.  I guess the best way to me to alleviate this problem is by being extremely specific as to what sites students can use.  When I put students on to use the Read About program, I feel confidant about that because I know that is exactly the site that students are using and nothing else.  The same thing goes for a math site like Sumdog or other educational sites.  The harder part comes when students are researching or looking up information on there own.  Depending on the topic of research, there are still sites that you can usually narrow it down to for students to find what they are looking for.  I prefer this than having students log on and just start to randomly search for things on google.....who knows what they will come across that way!?  This is something that I will continue to investigate and have discussions with colleagues about.  I am very interested in how other teachers handle this dilemma