To create assignments that work the focus must be on process, not task. Many constructivist learning theorists in the past have agreed on this, yet it remains a challenge. It's tempting to identify tasks, as they can be analyzed more easily, they're quantifiable and, therefore, gradable. Process-based learning is messier, takes longer to evaluate and, by definition, allows for many more variables than simple tasks. I do not mean that tasks are never to be assigned or evaluated. I mean that tasks are simply that--tasks. They do not necessarily demonstrate the learning of the student in the wider sense of the word. To shift the focus to process, however, we need to change what we value in our grading.
Via Dennis T OConnor