Even after repeated instruction, first year college chemistry students are often unable to apply stoichiometry knowledge to equilibrium and acid-base chemistry problems. The dynamic and interactive capabilities of online technology may facilitate stoichiometry instruction that promotes more meaningful learning. This study compares a technology-rich stoichiometry review course with a text-based study guide. The technology-rich course included: an overarching real-world story to both motivate the students and integrate ideas; the use of an exploratory virtual laboratory to support concept development and procedural practice; a variety of practice contexts; and feedback on both intermediate actions and submitted answers during student practice. The text-based study guide covered the same topics but without the dynamic interface, timely and informative feedback, or overarching storyline. Entering college freshmen volunteers were randomly assigned to either the technology-rich or the text-based materials. Analysis of post-test scores revealed a significant but small advantage for participants studying from the technology-rich course, but it was less important than the effects of SAT scores and gender. The degree of interaction with the Virtual Lab simulation was significantly directly related to post-test performance and eclipsed any effect of prior knowledge as measured by the SAT. (Contains 5 tables and 4 figures.)