Nowadays, outreach labs are important informal learning environments in science education. After summarizing research to goals outreach labs focus on, we describe our evidence-based gene technology lab as a model of a research-driven outreach program. Evaluation-based optimizations of hands-on teaching based on cognitive load theory (additional group discussions) and on conceptual change theory (consideration of students' alternative conceptions) achieved higher instructional efficiencies. We argue both modifications as generalizable for science teaching. As more general results, we describe identified student cognitive load types and problems of tutoring in hands-on teaching. Finally, we present our innovative approach of combining student and preservice teacher education, theory-based on pedagogical content knowledge by focusing on preservice teachers' change from student, to tutor, to teacher roles.