How can researchers in K–12 contexts stay true to the principles of rigorous evaluation designs within the constraints of classroom settings and limited funding? This paper explores this question by presenting a small-scale randomized controlled trial (RCT) designed to test the efficacy of curricular supplemental materials on epigenetics. The researchers asked whether the curricular materials improved students’ understanding of the content more than an alternative set of activities. The field test was conducted in a diverse public high school setting with 145 students who were randomly assigned to a treatment or comparison condition. Findings indicate that students in the treatment condition scored significantly higher on the posttest than did students in the comparison group (effect size: Cohen’s d = 0.40). The paper discusses the strengths and limitations of the RCT, the contextual factors that influenced its enactment, and recommendations for others wishing to conduct small-scale rigorous evaluations in educational settings. Our intention is for this paper to serve as a case study for university science faculty members who wish to employ scientifically rigorous evaluations in K–12 settings while limiting the scope and budget of their work.