For almost three decades the concept of adaptation of computer education has been an important topic. Approaches to giving the student a central role in his/her own learning process have been described in literature from early Computer Based Training systems to more recent Adaptive Learning Hypermedia Systems. However, the approaches have tended to be highly specific in their implementation, hampering comparison and extension of results in the field. The IMS Learning Design specification (IMS LD) addresses many requirements for computer based adaptation and personalized eLearning. In this paper we give an overview of a number of approaches, definitions and features of adaptive learning; in the second section we identify how adaptive features and elements can be addressed by IMS LD, detailing a number of example Units of Learning which illustrate adaptation in different ways. In the final section we discuss issues in attaining the right balance between effort invested and results acquired while modelling IMS LD adaptive Units of Learning.