There are several educational, social, and economic trends that converge to increase the need to understand how adolescents can best become more involved in the education of younger children. Many educators have pointed to the benefits of the rich and complex learning that occurs during cross-age tutoring. Current reforms in public school education feature an emphasis on teenage service to the community, including younger children, as an integral part of the high school program. Increased demands on parents to work outside the home have opened up new requirements for after-school day care for young children who can benefit from cross-age instruction. The literature on adolescents as educational instructors has emphasized the more limited role of "tutor" of material already presented rather than "teacher" of material new to the learner. This limitation has been described as being due to a restricted range of instructional moves, lack of sophistication in the tutor, and curricula which do not focus on the specific skills of the adolescent as an instructor. There is a need to better understand the potentialities of adolescents as science instructors for younger children. The purpose of this study done by the 4-H Youth Experiences in Science (YES) Project is to illuminate the interactions and other dynamics of adolescents as teachers in a science curriculum that was planned to use teenagers as the primary instructional source teachers rather than merely as tutors. This study found that the nature of child science (the instructional goal) was particularly well suited to the instructional strengths of teenagers. The adolescents were found to be effective at initiating exploration, play, manipulations, and testing of ideas and materials, all primary goals of child science learning. The implications of this study are important so that educators can plan curricula to take advantage of adolescents as effective instructors of child science. (Contains 29 references.) (DKM)