Tamara, Anyone who has ever lost a computer file due to failure to save it will recognize the benefit of having back-up plans for their lessons. Having several hours of instruction ruined because of computer glitches, burned-out LCD projector bulb, classroom occupied by others, misplaced curriculum binder, or a missing folder normally stored on the computer is really preventable by some proactive planning in advance. In these instances, these back-up plans are worth their weight in gold! Barry Westling