The roles of both positive and negative instances in concept formation are discussed. Based on research results, the article stresses ideas that the classroom teacher could try in order to aid concept learning. Several specific examples, based on the concept of commutivity, are given. (LS)

Analyzes multiplication word problems to identify the origin of children's difficulty. Emphasis is given to problems involving the concept of combination. (JN)

Discusses how to help children acquire mathematical concepts and teach for precise mathematical concepts. Describes four activities to reinforce the concepts introduced. (YP)

Indicates the shortcomings of paper-and-pencil tests. Reports the effect of an interview-and-teaching method for students who obtained correct answers by a mechanical process but lacked a conceptual foundation. Five references are listed. (YP)