Barry Richmond described seven systems thinking skills needed to become a successful systems thinker. These skills are woven throughout the grades 4-12 curriculum. The seven systems thinking skills can each be further defined by three distinct levels of competence, with an increase in cognitive capability required at each successive level. A proposed sequence is presented for the skills themselves, and suggestions are given for activities at each level within the skills. Level I activities may begin with ten-year-old students, but level II activities are best mastered by the senior students (about 18 years old). More research is needed to justify the proposed developmental sequence.