This booklet provides activities to enrich the core of basic mathematics instruction in the intermediate grades. Several learning center ideas are presented throughout the book, with general suggestions for the teacher in planning for and managing learning centers. The use of contracts with students is also discussed. Bulletin board ideas are included, along with a variety of activities grouped by content: place value and numeration, addition/subtraction, multiplication/division, fractions/decimals/percent, geometry, measurement, and graphing/statistics/probability. (MNS)