When I do progress grades, I decide what percentage of the project they
should have completed by that class, and then create a scale that I
carry around when I look at their projects.
For example, when I do paper-mache, I'll give a progress grade when the
armature should be finished, so if it is done they get a 100, if it is
almost done - 90, about 3/4 complete - 80, about 2/3 complete - 70,
about 1/2 complete - 55/60.
This helps remove some of the subjectivity from it - the kids can't say
"You don't like me, so you gave me a 70!" I can point to their work and
say that today they were supposed to at X point to get a 100, etc.
Hope this helps!
Pasadena High School