This booklet consists of 11 bulletins designed to answer questions which teachers frequently ask about the learning and teaching of mathematics. (The bulletins are revisions of a set originally published in 1970.) Each bulletin is organized around a central topic, and presents questions related to that topic, summaries of research findings relevant to each question, and a selected bibliography. The titles of the bulletins are: (1) Attitudes and Interests, (2) Organizing for Instruction, (3) Promoting Effective Instruction, (4) Differentiating Instruction, (5) Instructional Materials and Media, (6) Addition and Subtraction with Whole Numbers, (7) Multiplication and Division with Whole Numbers, (8) Rational Numbers: Fractions and Decimals, (9) Geometry and Other Mathematical Topics, (10) Verbal Problem Solving, and (11) Planning for Research in Schools. The volume is indexed by the questions answered in the bulletins, for easy reference. (SD)