User License
USER LICENSE:
By using these materials, you are agreeing to help us develop these optics 
laboratory materials. 

We base our license on the
Creative Commons Attribution-Noncommercial-Share Alike 3.0 License 
modified to include a share-back criterion:
Our modification of "share-back" includes that you agree to:
  - send Mark F. 
  Masters or Timothy T. 
  Grove an email telling us that you are using the materials. 
 Refer to the contact information (links above). In your email, be as specific 
  as possible about which materials you have used (or plan to use) in your class 
  and give us a report on what you did (if possible). This is extremely 
  important to us as we modify materials to be most appropriate for users.
  - "re-publish" any modifications you make by sending 
  them back to us (via email...). 
 We will update our materials if needed, or we will publish your version in 
  parallel here online. It helps to have descriptions of the modifications so 
  that future users can gain insight into your work.
 
  - Send any and all comments about the activity and 
  your experiences with it. 
 
By agreeing to 
the user license, you are helping us in our curriculum development and ensuring 
that high quality materials are created. We retain all publication rights to 
these materials, but are happy to share them as broadly as possible.