I have a generic rubric that I customize for each assignment. For an "A"
students must demonstrate effort beyond what is required to complete the
assignment on time. For A "B" students must demonstrate the effort
required to complete the assignment on time. For a "C" students
demonstrate effort less than what is necessary to complete the project on
time, "D" is minimal effort, etc. Other parts of the rubric address
design, ability to handle materials, etc. But I use this criteria to
differentiate between those who do just what they have to and those who
put more into their work.