Many students enter physics courses with highly intuitive conceptions of no
nobservable phenomena such as heat and temperature. The conceptions of heat
and temperature are usually poorly differentiated and heat is often confus
ed with internal energy. This article focuses on one student's cognitive an
d affective changes which occurred during the Grade 11 topic of heat and te
mperature. The instruction used an inquiry approach coupled with concept su
bstitution strategies aimed at restructuring alternative conceptions identi
fied using pretests. A constructivist perspective drove both the teaching a
nd research, and Ausubel's theory of meaningful learning augmented the inte
rpretive framework. The qualitative data comprising transcripts of all clas
sroom discussions, student portfolios containing all of each student's writ
ten work, and teacher/researcher observations and reflections were collecte
d and interpreted to generate a case study for one student named Ken. Ken's
initial conceptual framework was undifferentiated with respect to heat and
temperature. The course activities and concomitant use of concept substitu
tion helped him differentiate these concepts and integrate them in a more s
cientifically acceptable way. A degree of affective and epistemological cha
nge was also identified as the course progressed. In-depth examination of t
he student's prior, formative, and final conceptions showed that during thi
s unit, the student progressively accepted greater responsibility for his l
earning, was willing to take cognitive risks, and became more critical and
rigorous in both written and verbal problem solving. (C) 1999 John Wiley &
Sons, Inc.