If they don't, there is a copy of Davis Drive's Acceptable Use Policy on the SDPI web site. The easiest way to get around the acceptable use policy when using someone else's work is to just plan in advance and contact the owner explaining your intentions and asking permission. If you have permission, then you don't have to worry about whether or not you changed things enough or broke some portion of the code. Most people are willing to allow you to use there work for educational purposes under normal circumstances. When it is web material, you can just assign checking out the site to your students.
Most people are very eager to rack up the visitors to their site.