http://en.dha.ac.cn/
These incredible caves with their art still preserved after all thee years are a marvel to look at. This website has many resources. There are panorama images with a 365 degree feature (with zoom), there are also maps from the Silk Road, layouts of the site, and of course images. Many of the resources are in Chinese, but the images and features are still a good resource for students.
http://www.getty.edu/conservation/publications_resources/books/conserv_cave85.html
This website will take you to the Getty where you can purchase an art book on Cave #85, but it also has links to their information, photos, and articles about the caves as a whole. It's the Getty, so the site is appropriate for schools. Many of the resources talk about the workings of the restoration projects there.