Students will need to know that not everything online is true, be careful about your research and use reliable sources. Use databases instead of the first article that pops up in the search.
ISafe is a website that students could log on to and learn about Digital citizenship. I would start by asking them what do they know about being a good digital citizen and we can take it from there. I could also send a letter home with some of these websites so parents are aware of how to help their child with this as well.