Level 2

Alaska Science
Key Element

A student who meets the content standard should understand the scientific principles and models that describe the nature of physical, chemical, and nuclear reactions (Energy Transformations).


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Performance Standard Level 2, Ages 8–10

Students observe and describe physical and chemical changes to a system.

Sample Assessment Ideas

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Sample Assessment Ideas

  • Students examine and describe properties of non-Newtonian fluids (such as a mixture of water and corn starch a.k.a. “Oobleck”); compare with the properties of the starting substances.

  • Students saw a wooden board into pieces, compare properties; burn half the pieces; compare the resulting ash with the unburned pieces; account for gain or loss of volume and/or mass.

Expanded Sample Assessment Idea

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Expanded Sample Assessment Idea

  • Students investigate and report on several mixture systems to determine characteristics of physical and chemical change.


  • test tubes or well trays
  • chemicals in both solid and solution form, such as sodium chloride (salt), sodium bicarbonate (baking soda), acetic acid (white vinegar), silver nitrate

Suggestions for mix systems:

  • salt + water, stir
  • allow (1) to evaporate
  • baking soda + water, stir
  • allow (2) to evaporate
  • vinegar + solution (1)
  • vinegar + solution (3)
  • silver nitrate + solution (1)
  • silver nitrate + solution (3)


Students will:

  1. Observe and record appearance of substances before and after mixing,

  2. Observe and record behavior of substances during mixing.

Reflection and Revision

What properties do the substances have in common? What properties are different? What is evidence of physical change? What is evidence of chemical change? Which mixing operations fall into which category and why?


Levels of Performance

Stage 4
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Student response shows clear understanding of evidence regarding chemical reactions vs. physical changes taking place in matter rearrangements. Observations are thorough and interpreted with considerable detail and logical reasoning.
Stage 3
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Student response shows understanding of evidence regarding chemical reactions vs. physical changes taking place in matter rearrangements. Observations are thorough and interpreted with some evidence of logical reasoning. Minor errors may be present.
Stage 2
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Student response shows limited understanding of the difference between physical and chemical changes. Observations are minimal and interpreted with limited evidence of logical reasoning.
Stage 1
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Student response shows little understanding of physical or chemical change. Observations are minimal or totally incorrect, and interpretations show lack of scientific reasoning.
Standards Cross-Reference blue rule

Standards Cross-References
( Alaska Department of Education & Early Development Standards

National Science Education Standards

Substances react chemically in characteristic ways with other substances to form new substances (compounds) with different characteristic properties. In chemical reactions, the total mass is conserved. Substances often are placed in categories or groups if they react in similar ways; metals is an example of such a group. (Page 154)



Heating and cooling cause changes in the properties of materials. Many kinds of changes occur faster under hotter conditions. (Page 77)

When a new material is made by combining two or more materials, it has properties that are different from the original materials. For that reason, a lot of different materials can be made from a small number of basic kinds of materials. (Page 77)

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