Table 2
The Learning Progression for Changes in and Conservation of Matter
Achievement
Gaps/challenge
Instructional experience to support progression
Level 1 – Macroscopic compositional model (likely early elementary school)
Reshaping matter - A precursor to physical changes

• Realize that cutting an object into pieces that still have perceptual properties of the original material (e.g., a piece of paper cut into small pieces), or reshaping or reordering the object does not change the “amount" and the material type of the object. [Note that we emphasize a general notion of "amount of stuff" not quite conservation of mass here.]

Conservation of material identity and mass

• Student realizes that some solid materials can melt and the substances in the liquid form are still the same substance.


Key words: cutting; reshaping; melting
Reshaping matter

• Student may not realize that micro level small pieces, like sand grains or sawdust, still have mass and volume.

Conservation of material identity and mass

• Student may not realize that the material type does not change during melting process of all solid objects.
• Help students understand conservation of "amount of stuff" when grinding things into micro level pieces by engaging them in investigations that allow them to measure and record the mass during state change.

• Help students understand conservation of material identity across all melting and freezing events by allowing students to explore a range different materials that melt – not just water and ask students to predict and observe if material identity and or weight has changed during the process of melting.
Level 2 – Macroscopic compositional model (likely late elementary school)
Reshaping matter - A precursor to physical changes

• Student realizes that cutting and grinding into micro level pieces that do not have perceptual properties of the original object does not change the “amount" and the material type of the object. [Note that we emphasize a general notion of "amount of stuff" not quite conservation of mass here.]

Conservation of material identity and mass

• Student understands that all solid materials can melt and that a substance in liquid form is still the same substance.


Key words: grinding; melting
Conservation of material identity and mass

• Student may be unable to effectively predict conservation of mass during familiar physical changes (e.g., melting) and does not incorporate particles in models of physical change.
• Help students understand the conservation of mass during physical changes like melting by engaging them in investigations that allow them to measure and record the mass during state change and to analyze data from these investigations.

• Help students predict conservation of mass during physical changes by engaging them in investigations that allow them to measure and record the mass during state change.

• Help students develop a particle model for state change by engaging them in more opportunities to construct and revise models. Can also use multiple representations of physical change at the particle level to support student understanding.
Level 3 – Macroscopic compositional model (likely early middle school)
Reshaping matter - a precursor to physical changes

• Student realizes that mass and volume are conserved when reshaping, cutting, and grinding (e.g., when dividing matter into very small pieces).

Conservation of material identity and mass

• Student has the notion that type and number of particles (not distinguishing atoms from molecules) are conserved across some physical changes (e.g., melting, freezing). Therefore mass is conserved across some physical changes.


Key words: melting; freezing
Conservation of material identity and mass

• Student may be unable to effectively predict conservation of mass during all physical changes.
• Help students understand the conservation of mass during physical changes like boiling and evaporation by engaging them in investigations that allow them to measure and record the mass during state change and to analyze data from these investigations. May use computer simulations to trace particles.

• Help students apply a particle model across more cases of physical change by engaging them in more opportunities to construct and revise models.
Level 4 – Unidirectional particle model (likely early middle school)
Conservation of material identity and mass

• Student has the notion that type and number of particles are conserved across many physical changes consistently (e.g., dissolving, boiling, evaporation) but unidirectional. Therefore mass is conserved across many physical changes in some directions.


Key words: dissolving; boiling; evaporation
Conservation of material identity and mass

• Student may be unable to apply conservation of matter to all physical changes bidirectionally (e.g., matter is conserved in both evaporation and condensation).
• Help students understand that the conservation of mass is bidirectional in evaporation and condensation by engaging them in comparing open vs. covered cups experiments. May use computer simulations to represent particle models during evaporation and condensation processes.

• Help students apply a particle model directionally across all physical changes by engaging them in more opportunities to construct and revise models.
Level 5 – Bidirectional particle model (likely late middle school)
Conservation of material identity and mass

• Student has the notion that particles are conserved across all physical changes bidirectionally (e.g., both evaporation and condensation). Therefore mass is conserved across all physical changes in all directions.


Key words: physical change; evaporation; condensation
Conservation of material identity and mass

• Student may be unable to apply conservation of matter to chemical changes.

Energy during change

• Student may not recognize that some chemical reactions release energy and some absorb thermal energy.
• Help students understand that the conservation of mass applies to chemical changes. May use computer simulations to predict and test what chemical components are present before and after certain chemical reactions. Can also use multiple representations of chemical changes to support student understanding.

• Help students apply a particle model across chemical changes by engaging them in more opportunities to construct and revise models.

• Help students understand that energy is included in chemical change. May ask students to measure the change in temperature after a chemical reaction and then ask them to construct an explanation by using computer simulations that explore micro level phenomena.
Level 6 – Atomic-molecular model (likely late middle school or late high school)
Conservation of material identity and mass

• Student has the descriptive notion that the number and type of atoms are conserved during chemical change.

• Student can apply conservation of mass across all physical and chemical changes in all directions.


Key words: physical change; evaporation; condensation
Energy during change

• Student may not include mechanistic accounts (e.g., attractive forces within and between molecules) for physical and chemical changes.

Energy during change

• Student recognizes that some chemical reactions release energy and some absorb thermal energy.
N/A

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