The study described in this paper outlines an attempt to explore those factors that contribute to learning performance improvement in laboratory instruction. As a case study, the educational methodology involved in a basic microcontroller course was analyzed. Traditional lab sessions based on the control of peripherals with low interactivity have been replaced with new sessions based on mobile technology and the Short Message Service (SMS). This allows the development of greater interactivity and the provision of more motivating features. Using the key tenets of the three basic learning theories (behaviorist, cognitivist and constructivist) and the notion of interactivity as causal factors, the study described in this paper presents a performance learning model based on the theory of reasoned action. This learning model identifies the variables with a significant influence on the learning performance, allowing a statistical analysis to quantify their influence. The results obtained demonstrate the important roles of interactivity and motivating features in a laboratory instruction from both a qualitative and a quantitative point of view. (Contains 5 figures and 4 tables.)