Research on learning has shown that students learn differently and that they prefer to use different type of resources. Adaptive Educational Systems can support different learning characteristics by building a model of the student?s learning behaviour and subsequently adapting the learning environment to match different needs. However major challenges exist, as it is not clear how a student model of learning style can be accurately built. One solution may be in the use of machine learning techniques. This paper presents ?First Aid For you?, a novel adaptive educational system that dynamically determines learning style using machine learning techniques. The paper describes how it uses the Felder & Solomon Index of Learning Style to design an environment for different learning styles. It also describes how, as the student interacts with the learning environment, it uses the Na?ve Bayes algorithm to predict the student?s preferred learning style and adaptively customize the learning environment