The focus of this paper is the application of the theory of contingent tuto
ring to the design of a computer-based system designed to support learning
in aspects of algebra. Analyses of interactions between a computer-based tu
toring system and 42, 14- and 15-year-old pupils are used to explore and ex
plain the relations between individual differences in learner-tutor interac
tion, learners' prior knowledge and learning outcomes. Parallels between th
e results of these analyses and empirical investigations of help seeking in
adult-child tutoring are drawn out. The theoretical significance of help s
eeking as a basis for studying the impact of individual learner differences
in the collaborative construction of 'zones of proximal development' is as
sessed. In addition to demonstrating the significance of detailed analyses
of learner-system interaction as a basis for inferences about learning proc
esses, the investigation also attempts to show the value of exploiting meas
ures of on-line help seeking as a means of assessing learning transfer. Fin
ally, the implications of the findings for contingency theory are discussed
, and the theoretical and practical benefits of integrating psychometric as
sessment, interaction process analyses, and knowledge-based learner modelli
ng in the design and evaluation of computer-based tutoring are explored. (C
) 2000 Published by Elsevier Science Ltd. All rights reserved.