I understand how helpful samples are when experimenting with using new technologies for learning. Even after you have a clear picture of how you want to use a new tool in your class, you will soon ask, "Hmmm...and how am I going to grade the activity?"
Rubrics can be very helpful to instructors and students. When you develop a rubric for an assignment, it forces you to make important decisions about the criteria you will use to assign credit. It's helpful to make a brief list of the criteria categories (keep them simple and few for quick grading -- if there is such a thing) and then distribute a maximum number of points to each criteria category. Then ask yourself to identify what qualifies for "partial" and "full" points in each criteria category.
Share each rubric with your students before the activity begins so they have an opportunity to review what your expectations are. Include a note on the rubric to your students that clearly states you will be using the rubric to grade their activities/assignments. You'll find that this will dramatically reduce the "grade negotiation" sessions in your life and students will appreciate understanding exactly what you expect of them.
In an effort to help, I'm sharing a simple VoiceThread rubric that may be a resource for you or someone you know. I've shared it under a CC0 public domain mark which releases it into the public domain (i.e. you don't need to attribute me if you use it in your own class).
Click here to download the VoiceThread Rubric.