Web Based Laboratory Simulations- Any Suggestions?

I have been considering supplementing or replacing some of the core labs from my prescribed middle School Science curriculum with virtual simulations. I realize the importance of hands on laboratory work and would not consider abandoning the actual wet lab in its entirety but I would like to experiment with some virtual simulations which I suspect , if used appropriately might actually provide increased engagement and possibly a more in depth understanding of the concepts being presented. However, I am faced with the dilemma that my department has provided core labs which must be completed and I do not have the luxury of sufficient instructional time to complete hands on core labs in addition to virtual simulations. My programming knowledge is limited to say the least and to date I have been unsuccessful in finding a web based lab platform which provides the flexibility to adapt virtual labs so that they correspond with the department of Education Core Labs. Has anyone had success with user friendly web based laboratory software which would provide varied simulations some measure of flexibility with respect to experimental design. Your suggestions would be greatly appreciated. Thanks Trevor