The Rational Number Project (RNP) is a cooperative research and development project funded by the National Science Foundation. Project personnel have been investigating children$\rq$s learning of fractions, ratios, decimals and proportionality since 1979. The book is the product of several years of working with childrens in classrooms trying to understand how to organize instruction so students develop a deep, conceptual understanding for fractions. The given 23 lessons were originally developed for this research. Content: (I) Teacher$\rq$s Guide; (II) The RNP Lessons: Level 1; (III) Appendix - Fraction Circles and Assessment Ideas.