  We have investigated the long-term effect of student-centered instruction at
the freshman level on juniors' performance on a conceptual survey of
Electricity and Magnetism (E&M). We measured student performance on a
research-based conceptual instrument -- the Brief Electricity & Magnetism
Assessment (BEMA) -- over a period of 8 semesters (2004-2007). Concurrently, we
introduced the University of Washington's Tutorials in Introductory Physics as
part of our standard freshman curriculum. Freshmen took the BEMA before and
after this Tutorial-based introductory course, and juniors took it after
completion of their traditional junior-level E&M I and E&M II courses. We find
that, on average, individual BEMA scores do not change significantly after
completion of the introductory course - neither from the freshman to the junior
year, nor from upper-division E&M I to E&M II. However, we find that juniors
who had completed a non-Tutorial freshman course scored significantly lower on
the (post upper-division) BEMA than those who had completed the reformed
freshman course - indicating a long-term positive impact of freshman Tutorials
on conceptual understanding.
