We present a concrete situation where there is a difference between the theoretical security of a cipher and its limitations when implemented in practice. Specifically, when entering a PIN, smudges on the keypad substantially reduce its security. We show how the number of possible keys in the presence of the "smudge attack" can be…

Describes the experience of a bilingual kindergarten teacher who, in an effort to improve students' writing, used color-coded symbols familiar to students on specific key functions of the computer keyboard. Familiarity with the keyboard functions facilitated the children's understanding and consequent use of software, and allowed the children to…