Empirical evaluations suggest that use of interactive technologies can reduce the costs of instruction by about one-third. In addition, they can either increase achievement by about one-third while holding time constant or reduce time needed to achieve targeted instructional objectives by about one-third. These technologies can be delivered over the Web, which can also support systems that generate instruction on demand. Development of either generative instruction or pre-specified interactions will benefi t from a ready supply of instructional objects such as those specified by the Sharable Content Object Reference Model (SCORM), which is now receiving wide, international acceptance. SCORM will be further enhanced by the development of the Semantic Web, which will allow more extensive links between available representations of knowledge and enhance the discovery of learning objects for use in instruction.