  We add to a growing literature suggesting that demographic grade gaps should
be attributed to biases embedded in the courses themselves. Changes in the
structure of two different introductory physics classes were made while leaving
the topics covered and the level of coverage unchanged. First, a class where
conceptual issues were studied before doing any complicated calculations had
zero final exam grade gap between students from underrepresented racial/ethnic
groups and their peers. Next, four classes that offered students a retake exam
each week between the regular bi-weekly exams during the term had zero gender
gap in course grades. Our analysis indicates that demographic grade gaps can be
attributed to the course structure (a Course Deficit Model) rather than to
student preparation (a Student Deficit Model).
