Multi-media instruction can invoke multi-tasking in learners on voluntary and involuntary levels. Several information channels may be in operation and may be activated consciously or unconsciously. During learning, one or more channels may be utilizing the maximum cognitive resources available. Under those conditions, cross-channel interference may be more likely. In light of the phenomena of voluntary and involuntary initiation of cognitive tasks by multi-media presentations are multi- or mono-media instructional materials more efficacious to learners? Why