The importance of developing reasoning and justification has been highlighted in "Principles and Standards for School Mathematics" (NCTM 2000). The Common Core State Standards for Mathematics (CCSSI 2010) further reiterates the importance of reasoning and proof in several standards for mathematical practice. Students of all grades are…

The relation between the area of a rectangle and its perimeter is clarified by looking at patterns. Several examples involving rectangles with integral sides are presented. (MNS)

Tree diagrams with numbers in a given pattern generate questions related to pattern recognition and number concepts such as binary numbers and exponentials. (MP)

An activity project is described which encourages students to question and experiment. Appendices provide examples of student results. (MNS)

Mathematical proofs often leave students unconvinced or without understanding of what has been proved, because they provide no visual-geometric representation. Presented are geometric models for the finite geometric series when r is a whole number, and the infinite geometric series when r is the reciprocal of a whole number. (MNS)

Briefly presented are suggestions on using exercises in number patterns in second-year algebra and factoring quadratics in a 10th-grade enrichment class. (MNS)

A computer program is presented for the billiard ball problem. It can be integrated into a lesson on inductive reasoning and suggests several ways to do so. (MNS)

Described are two examples involving recursive mathematical sequences designed to integrate a holistic approach to learning algebra. These examples promote pattern recognition with algebraic justification, full class participation, and mathematical values that can be transferred to other situations. (MDH)

Brief articles are included on exploring mathematical patterns, with two computer programs listed for finding happy numbers; a simple periodic function in trigonometry; and comments on humorous student errors. (MNS)

How to find and classify positive integral solutions to 1/a + 1/b = 1/c in beginning and advanced algebra classes is described. The computer finds the solutions, but students practice algebraic manipulation as they analyze the solutions for patterns. Extensions to challenge more capable students are included. (MNS)

Activities to extend the core curriculum through the study of the periodicity of rational numbers to help students develop calculator and research skills are presented. Four worksheets are included, to be used as discovery activities. A computer program is listed, as well as examples of periodic pictures. (MNS)

Described are activities that use a hundred chart to improve student abilities to recognize and describe number patterns, to use variables, to make and informally prove conjectures, and to communicate mathematical ideas to classmates. Included are the directions, four reproducible student sheets, the answers, and extensions. (KR)