Presented are a series of conjectures and proofs resulting from an examination of patterns and relationships among natural numbers. (JP)

Sorting activities for multiplication and division facts are suggested for developing concepts of prime factors. (MP)

Included are nine brief notes on various aspects of infinity. These are an attempt to stimulate and organize the thinking of teachers and others who acknowledge the role notions of infinity play in mathematics and in children's thinking. (MK)

An approach is illustrated that introduces selected models of addition and subtraction to students who have previously learned a model for either operation. (JT)

Shows how all primitive Pythagorean triples can be generated from harmonic sequences. Use inductive and deductive reasoning to explore how Pythagorean triples are connected with another area of mathematics. (KHR)

Suggested are investigations for junior and senior high school students that may lead to discoveries and at the same time provide a variety of practice in computing with fractions. (JP)

A classroom exercise which encourages experimentation including formulation and testing of conjectures about number relationships involving factors and multiples is illustrated. (MN)