Grades 2–5 | Heat Transfer & Engineering DesignLooking for a fun, hands-on Valentine’s Day STEM activity that goes beyond crafts? In this engaging mini-lab, students take on an engineering challenge: Can you design an insulator to keep a chocolate heart from melting?This low-prep, classroom-tested activity helps students explore heat transfer, insulation, and material properties while practicing prediction, observation, and reflection — all with a Valentine’s Day twist. What’s Included ✔