Student perceptions of classroom environment can provide useful criteria for evaluating educational alternatives. The My Class Inventory (MCI) was used with 588 3rd- to 5th-grade students in Texas in evaluating the effectiveness of instruction using a textbook, science kits, or a combination of both. Various analyses attested to the factorial validity and reliability of the MCI and suggested that using science kits was associated with a more positive learning environment in terms of student satisfaction and cohesiveness. Higher student satisfaction was found in classrooms with greater cohesiveness and less friction and competition. Qualitative data generally supported the findings from surveys. (Contains 1 figure and 4 tables.)