Recent research suggests that many middle school students approach mathematical story problems with strategies that are not based on possible meanings for the operations, yielding success for one-step problems, but providing a weak background for approaching algebra story problems. This document reports the findings and the materials developed by a National Science Foundation (NSF) funded project to supplement textbook offerings and to give a greater emphasis to meanings for the operations. The materials were field tested with middle school students and revised after consultation with an advisory panel. Despite success in helping some students, the immature strategies are resistant to change for many middle schoolers. The document is divided into two sections. The first section is the NSF final project report, containing project identification information, a summary of the completed project, technical information including the projects background and procedures, and a list of the project personnel. The second section, "Project Materials," contains the developed materials. The preface in this section discusses the underlying assumptions employed in developing the materials, types of contextual settings used for applications of addition, subtraction, multiplication, and division, and uses of open-ended lessons. The lessons are presented under six headings, mainly by operation, identifying "meaning-centered" lessons for a given setting that should be studied before "application" lessons are undertaken. The six headings are: (1) Number Sense; (2) Addition; (3) Subtraction; (4) Multiplication; (5) Division; and (6) Situational or Open-ended. (MDH)