Assessment of project based learning remains somewhat of a mystery, because we have few models of assessment systems that match with project-based curricula and student-centered instruction. Our GLEF Agenda advocates for a full spectrum view of assessment, what we call comprehensive assessment. This vacuum around improving assessment limits development of better curriculum and instruction, because assessment drives instruction. What gets measured gets taught. And, as Einstein indirectly observed, it's become too convenient to confine assessment to counting test scores.
We know that the typical multiple-choice and short-answer tests aren't the only way, or necessarily the best way, to gauge a student's knowledge and abilities. Many states are incorporating performance-based assessments into their standardized tests or adding assessment vehicles such as student portfolios and presentations as additional measures of student understanding.