The differential effects of online student-constructed tests (SCT) and student-generated questions (SGQ) strategies on knowledge construction in term of the breadth, depth, interconnectivity and elaboration of knowledge were examined via a quasi-experimental research design. Two classes of undergraduates (N = 65) participated and were randomly assigned to two different treatment groups. An online system supporting the associated learning activities for the respective groups was developed. The results from the ANCOVA showed that students who engaged in SCT activities generated questions that covered significantly more concepts, involved significantly more levels of subordinate concepts, and built significantly more links between clusters of study topics, as compared to those in the SGQ group. Moreover, significantly more students in the SCT group engaged in item revision behavior than those in the SGQ group, and a majority of students in the SCT group exhibited item sequencing behavior, both of which are deemed indicative of knowledge elaboration. Suggestions and implications for instructional implementation, online system development and future studies are offered.