Principles Five and Six
Definition: The design minimizes hazards and the adverse consequences of accidental or unintended actions.
Just as a double-cut key may be inserted right-side-up or upside-down, and thus tolerates error (unlike regular keys which must be inserted right-side-up), so, too, does a word-processing program that takes advantage of the "Undo" command in Windows operating systems.
Students with arthritis, cerebral palsy, quadriplegia, and other conditions limiting fine-motor control often will benefit considerably from the use of a "keyguard." This is a plastic sheet that fits over a keyboard. The sheet itself offers a resting place for hands and wrists, such that hands do not unintentionally strike keys. Above each key is a hole in the plastic sheet; users insert a finger into that hole to activate the key. This ensures that only the "correct" key is pressed. Keyguards are simple, one-piece products, yet, because relatively few are sold each year, are priced at high levels; your students should expect to pay $100 or even more for a keyguard.
ZoomCaps and other key letters/numbers having larger, more readable characters are readily available from such sources as Maxi Aids (1-800-522- 6294) and Flaghouse (1-800-793-7900). They reduce error because people can more easily identify what each key does.