How Chemical Reactions Conserve Mass

Crash Course Kids

This engaging video explores the Law of Conservation of Mass specifically through the lens of chemical changes. Using Lego bricks as an accessible analogy, the host demonstrates how atoms (represented by blocks) are merely rearranged rather than created or destroyed during reactions. This visual metaphor helps bridge the gap between abstract atomic theory and observable phenomena. The video moves from theory to practice by conducting a "gross" but effective experiment mixing vinegar and cream to create curds. It introduces critical scientific vocabulary including reactants, products, and chemical changes, while teaching students how to identify evidence of reactions such as temperature shifts, bubbling, or light. The host also addresses the tricky concept of conserving mass when gases are produced, referencing closed systems like balloons. For educators, this resource serves as an excellent anchor for units on matter and chemical reactions. It directly addresses Next Generation Science Standards regarding conservation of matter (5-PS1-2 and MS-PS1-5). The combination of a concrete model (Legos) and a wet lab demonstration makes it perfect for visual learners and provides a clear framework for students to design their own investigations into mass conservation.