Rather than reinvent the wheel, I wanted to pass along a link to a website that has a list of 7 science-related educational tools as well as descriptions for each of the websites. I have used Learning Never Stops, the website I found it on, before for their great compilations of all thing technology for education. One of my favorite sites in their science list is Sellafield Ltd's education resources page, which has a long list of activities complete with PDF downloads, games, videos, etc. to make them an easy way to add variety to your science classroom. Check it out and let me know what you think!
I had a teacher ask me if there was a way to hide or remove students who are no longer in your class. The answer is maybe. It depends on if they are officially dropped from your class and appearing as red in your roster and gradebook. If not, then no, you cannot remove them until they have been unenrolled from the class. If the student is showing up as red in your gradebook though, you can hide them so you don't have to worry about them. Here is a screenshot to help you do it: