Mechanistic explanations aim to reveal intricate details by unpacking entities and their activities. However, all mechanistic explanations also contain explanatory black boxes, informational units hiding mechanistic details. While these knowledge gaps could be considered an obstacle to mechanistic reasoning, we recognized them as inevitable and productive to it. We begin this chapter by introducing black boxes’ relevance to science teaching. We discuss their origin in the science classroom and their possible effect on students’ mechanistic reasoning. Following, we draw insights from a study in which twenty-three 10th-grade biotechnology students were familiarized with the ‘black-box’ term during a 14-hour online unit. As a summative assignment, the students created informational posters, during which we asked them to articulate considerations for their unpacking and black boxing decisions. Our findings point to a correct use of terms in most cases, suggesting students’ understanding of them. Additionally, using bottom-up analysis, we found that cases addressing black boxing decisions presented a more complex approach than those addressing unpacking decisions, as they included a comparison between several black boxes. This chapter highlights the importance of integrating black box explication into science education to promote a deeper comprehension of the nature of science and mechanistic reasoning.