An instructional program using four simulation applets was used to facilitate understanding of gas and liquid pressure concepts among twenty-two students in a Year 9 class from an independent secondary school in Singapore. A comparison group consisting of twenty-two students was taught using traditional didactic, chalk-and-talk instruction. Administration of a gas and liquid pressure conceptual test comprising ten multiple-choice items in a pretest-posttest design indicated significant improvement in understanding using the simulation applets compared to the didactic instruction. A seven-item attitudes questionnaire indicated that the students generally found the animation applets interesting and helpful in their physics lessons. (Contains 4 figures and 2 tables.)