This report investigated to what extent a curriculum designed to actively teach critical thinking skills resulted in students utilizing higher-order thinking skills (e.g., analysis, synthesis and evaluation). An intervention strategy was designed for a sixth grade class located in a diverse suburban community in northern Illinois. The intervention targeted the mathematics curriculum and was designed to incorporate the teaching of critical thinking skills. Students were administered a pretest to determine baseline data. The intervention included the daily use of a variety of thinking skill enhancers and guided assessment of problem-solving strategies for a twenty-week period. Results indicated success on many levels. Students displayed increased self-esteem and confidence in their abilities to problem-solve. Self-reflection of their work was also observed. Students were able to verbalize their thought processes in analyzing problems. As an indicator of success, however, it was hoped that there would have been a higher number of students displaying an increase in posttest results. Nevertheless, with over fifty percent of the students involved in the intervention showing increased scores, the time and energy expended in this project were affirmed. (Contains 13 references.) (Author/YDS)