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AAS.SC15.5.2 Recognize that regardless of the type of reaction (e.g., new substance forming due to dissolving or mixing) or change (e.g., phase change) that occurs when heating, cooling, or mixing substances, the total weight of the matter is conserved.

Unpacked Content

Scientific and Engineering Practices

Using Mathematics and Computational Thinking

Crosscutting Concepts

Scale, Proportion, and Quantity


Students know:
  • The amount (weight) of matter is conserved when it changes form, even in transitions in which it seems to vanish.
  • No matter what reaction or change in properties occurs, the total weight of the substances does not change. (Boundary: Mass and weight are not distinguished at this grade level.)


Students are able to:
  • Measure and graph the given quantities using standard units, including: the weight of substances before they are heated, cooled, or mixed and the weight of substances, including any new substances produced by a reaction, after they are heated, cooled, or mixed.
  • Measure and/or calculate the difference between the total weight of the substances (using standard units) before and after they are heated, cooled, and/or mixed.
  • Describe the changes in properties they observe during and/or after heating, cooling, or mixing substances.
  • Use their measurements and calculations to describe that the total weights of the substances did not change, regardless of the reaction or changes in properties that were observed.
  • Use measurements and descriptions of weight, as well as the assumption of consistent patterns in natural systems, to describe evidence to address scientific questions about the conservation of the amount of matter, including the idea that the total weight of matter is conserved after heating, cooling, or mixing substances.


Students understand that:
  • Standard units are used to measure and describe physical quantities such as weight and can be used to demonstrate the conservation of the total weight of matter.


  • Quantitative measurements (mass, weight, standard unit)
  • Physical quantities (weight, time, temperature, volume)
  • Property changes
  • Matter
  • Reaction
  • Heating
  • Cooling
  • Mixing
  • Physical properties
  • Conservation of matter
  • Graphing