Tying the technology to objective makes its use relevant and it serves as a tool to achieving mastery.
We should hold students accountable for the stations/centers to assure that they are contributing individually to the activity assigned to their stations. Student accountability helps the teacher know whether individual student at the station has achieved mastery of the content objective.
I like the following sites:
Angles and Pararell Lines 7 applets.
Students in a station will have assignments with different levels of difficulty. When done, students will print and turn in the assignments they have completed. Teacher knows who did what based on assigned levels of difficulty. I have special education students that I work with on one-on-one.