Within high school chemistry the topic of acids, bases, and pH is particularly challenging because robust understanding of the topic depends heavily on the student possessing deep concepts of atoms, molecules, ions, and chemical reactions. Since knowledge is acquired and stored in a dynamic structure, it was investigated in this study how knowledge changed as a result of the student's exposure to a particular type of learning task. Two areas of interest were targeted: the change in the students' understanding of acids, bases, and pH over the course of the treatment and the type of thought processes in which the students engaged while performing the treatment tasks. These understandings and thought processes were followed as a function of three levels of information presented by the technology: low level as represented by the use of chemical indicator solutions, intermediate level as represented by the use of a pH meter, and high level as represented by the use of a microcomputer-interfaced electronic pH probe. Reported in this paper are students' understandings prior to and after interacting with these technologies. Verbal data and drawings obtained in clinical interviews were used to construct concept maps and to analyze students' molecular concepts. Experts were also interviewed, and their concept maps were analyzed to identify critical nodes on their understanding of acids, bases, and pH. The concept maps and drawings were analyzed and two general conclusions reached: (1) students using microcomputer-based laboratory (MBL) activities appeared to construct more powerful and more meaningful chemical concepts; (2) the microcomputer group's high rates of both erroneous and acceptable links provide evidence that these students were positively engaged in restructuring their chemical knowledge. MBL appears to help students develop deeper understanding of acids, bases, and pH concepts, as indicated by the concept maps showing more detailed differentiation and integration. Examples of student's and expert's concept maps are appended. (KR)