Content Focus: Conservation of Matter

Key Content Ideas (3-5)
• Regardless the type of matter change, the mass before and after the change stays the same.
• The SPM supports that matter is conserved in change (e.g., mixing substances)

This sub-area focuses on the conservation of matter during physical and chemical changes. Measurements of mass provide evidence that regardless of the type of change, the total amount of matter does not change. (Boundary: In grades K-5, mass and weight are not distinguished.)

Although this sub-area is typically not addressed until upper elementary, in K-2 the manipulation of a finite number of building blocks can introduce students to the concept of conservation of matter. In grades 3-5, this sub-area involves the measurement of the weights of substances before and after heating, cooling, or mixing. This sub-area also involves graphing data and performing calculations to support the idea that matter is conserved. Simple experiments to demonstrate the conservation of matter include the melting and freezing of water and the dissolving salt or sugar in water. Some experiments can be designed to address misconceptions such as gases have no weight. For example, the reaction between baking soda and vinegar can be conducted in both sealed and open containers, and the changes in the total weights can be compared.