The constructivist view of learning pays special attention to students' pri
or knowledge. One of the core statements of this view is the necessity of c
onnecting students' prior knowledge with the new contents to be taught. Bas
ed on this idea, research on conceptual change explored students' prior con
ceptions overall about scientific phenomena, and instructional strategies w
ere developed to promote conceptual change. One of the most common conceptu
al change instructional strategies implemented in the classroom was to indu
ce cognitive conflict through presenting anomalous data or contradictory in
formation. First, the paper presents a review of the conceptual change theo
retical frameworks that support this strategy. Second, a review of the cont
roversial results obtained in the application of the cognitive conflict str
ategy in the classroom is presented. Third, a discussion of the possible fa
ctors that may explain the difficulties to implement this strategy is intro
duced. Three kinds of problems may explain these difficulties. The first ki
nd of problem is related to the question about how to make the cognitive co
nflict meaningful for students. Motivational factors, epistemological belie
fs, prior knowledge, values and attitudes, learning strategies and cognitiv
e engagement, and reasoning strategies, as well as social factors, seem to
be relevant to lead students to a meaningful conflict. The second kind of p
roblem is linked to more general theoretical and methodological aspects tha
t research on conceptual change still has to solve. Finally, a third group
of practical problems related to the implementation of the cognitive confli
ct strategy in real school settings is presented. (C) 2001 Elsevier Science
Ltd. All rights reserved.