PhET Interactive Simulations requires that all submitted content (lessons, activities, etc.) be available under an Open Content license that allows others to use, distribute, and create derivative works based upon that content. The Creative Commons Attribution License fulfills this requirement, while still allowing authors to receive credit for their efforts.
I hereby allow PhET Interactive Simulations to distribute this content under the terms of the Creative Commons Attribution License available at http://creativecommons.org/licenses/by/4.0/. I understand that in doing so I
1. retain my copyright in the work and
2. warrant that I am the author or the owner or have permission to distribute the work in question and
3. wish this work to be distributed under the terms of that license (including allowing modification of this work and requiring attribution) and
4. agree that proper attribution of my work is any attribution that includes the authors' names, the title of the work, and the PhET Interactive Simulations’ URL link to the work.
I hereby allow PhET Interactive Simulations to distribute this content under the terms of the Creative Commons Attribution License available at http://creativecommons.org/licenses/by/4.0/. I understand that in doing so I
1. retain my copyright in the work and
2. warrant that I am the author or the owner or have permission to distribute the work in question and
3. wish this work to be distributed under the terms of that license (including allowing modification of this work and requiring attribution) and
4. agree that proper attribution of my work is any attribution that includes the authors' names, the title of the work, and the PhET Interactive Simulations’ URL link to the work.