ChemBotCap: A Kit Based on Snap-Top Bottle Caps to Learn about Simple Molecules

Understanding molecular structure is fundamental in chemistry education. However, commercially available molecular model kits are often expensive and are not always present in educational institutions. Here we present ChemBotCap, an innovative, low-cost, and engaging alternative for modeling simple inorganic and organic molecules using repurposed snap-top plastic bottle caps. The design leverages the built-in hinge mechanism of these caps, allowing students to physically assemble molecular structures and explore concepts such as covalent bonding, molecular geometry, connectivity, and functional groups. ChemBotCap was implemented in a university-level science education course for preservice teachers. Students worked collaboratively to model a set of assigned molecules, reinforcing their understanding of structural formulas and molecular geometry. Feedback collected through a questionnaire after using ChemBotCap indicated high levels of engagement, conceptual clarity, and perceived educational value.