When I am looking at a web site to use with my second grade students, the main draw for me is if its content is going to enhance their learning in some way. I want them to use web sites to help them discover new learning, to explore the site to find answers to questions they have, or to provide practice for them to become better in their skills.
Another aspect that is important for me is that the site is easy to navigate and has been set up so that it is user friendly for their grade level. The font style and the size should be easy for them to read so they are understanding the content. Also sites that have images, video, audio and a way to interact are best to sustain their interest and to teach them new information. The more they can do or see the better.
For both teachers and students the information must be authentic and accurate. The source of the information must be reliable. I send along websites to my colleagues that I find interesting when they give information about a topic that I know other teachers are using or would find helpful in their teaching. Teachers also seem to prefer video demonstrations of topic especially when they can see teachers or students in action demonstrating a topic in a real situation. Essentially, if I value the web site then I try to share it with someone else who I think it would be useful to also.