This is one form of three performance checks booklets (A, B, and C) for two texts of Level III of the Intermediate Science Curriculum Study (ISCS). These two texts are In Orbit (IO), and What's Up (WU). The 12 performance checks booklets for Level III are considered one of four major subdivisions of a set of individualized evaluation materials for Level III of the ISCS. This booklet (form C), developed to assess the students' achievement of the objectives of IO and WU of Level III, contains a set of performance checks which are equivalent to the performance checks of the other two forms (A and B). Each performance check has its own code number and identifies whether it is based on core material or excursions. Directions for students' use of performance checks are also included. (HM)