Starting from the concept of one-to-one correspondence, an introduction to the different types of infinities is presented. The usual problems concerning the infiniteness of the rational numbers, the real numbers, and the unit interval are given. Several other theorems follow. (LS)

Illustrations of the misuse of the associative property in elementary school texts are given; the question is raised as to the appropriateness of stressing the commutative and associative properties at the elementary level. (DT)

Describes secret messages'' using codes suitable for any level; examples. (SP)

Described are patterns in Pascal's triangle which are obtained when the entries are reduced modulo a prime number. (MM)

Problems involving infinity and paradoxes are included in a discussion of how students can be exposed to the human element of mathematics. (DT)

Utilizes two interpretations for the positive and negative signs to demonstrate how multiplication and division involving negative numbers can be represented and their inverse nature illustrated. (RP)