A key element of this project is to promote sharing and reuse of teaching material among educators. In order to lower the barriers raised by copyrights and the associated confusion over whether "fair use" applies, we strive to offer all the materials in our shared collection under a license that explicitly allows for this sort of reuse. This Creative Commons Attribution Non-Commercial license allows for reuse of materials on the site as long as attribution is given to the original author and the material isn't used for a commercial purpose (e.g. included within a textbook that is offered for sale).

To make this happen each contributor must grant us permission to offer their contribution up under this sort of license. In submitting your materials you are agreeing to this arrangement. It's important to note that we assume all materials you provide (either text or uploaded files and images) are either created by you or are offered up by their original creator in a fashion that is commensurate with this redistribution. If your contribution contains materials created by others (images, documents) you must have the permission of the original author (either explicitly given to you, or given implicitly by virtue of the material being in the public domain, or offered up under some similar license) in order to contribute them to this collection

What did all that mean? Questions and Answers

Does this mean I'm giving up my copyright/ownership of what I contribute?

No. Contributors to these activity collections retain their copyright of the things they contributed. They are free to do whatever they like with their materials (e.g. including it in a textbook for sale). The license contributors are agreeing to simply outline the limits of what we can do with the materials (and by extension what people who find the materials through the collection can do, without having to go back to the author and ask for broader permissions).