The cookbook-style implementation of practical experiments in schools and colleges has prompted a critical re-evaluation of their values and needs. Various studies have revealed that the use of new technologies, e.g., computer simulation, in practical experiments does not necessarily result in learning enhancements. In fact, in some cases, the opposite happened. In the present article, I will describe and discuss a case where a computer simulation was used to help students learn practical skills in a pre-lab. The result of this investigation indicates that the use of virtual lab actually gives rise to virtual, rather than real, understanding.