The document discusses five types of learning objects (LOs) defined by David Wiley: 1) Fundamental - individual digital resources like images 2) Combined-closed - small numbers of digital resources combined for a single purpose 3) Combined-open - large numbers of digital resources combined in real time and reused 4) Generative-presentation - network accessible objects combined to recreate presentations 5) Generative-instructional - combines and evaluates student interaction with object combinations