An important part of Digital Citizenship is understanding copyright, especially when it comes to images. SO many students just pull images from any website with no regard for whether they are copyrighted or not. This article has a lot of information on "Copyright curriculum for kids".
How to search Flickr for free images to use with students/ for students to use. This is something I am really making a big effort to work on this year in class - teaching about copyright and fair use for their presentation.