Unit Overview

In the Chemical and Physical Changes unit, students are led through a progression of three inquiry lessons that focus on the the differences between physical and chemical changes

• Next Generation Science Standards

  MS-PS1-2

  Analyze and interpret data on the properties of substances before and after the substances interact to determine if a chemical reaction has occurred. [Clarification Statement: Examples of reactions could include burning sugar or steel wool, fat reacting with sodium hydroxide, and mixing zinc with hydrogen chloride.] [Assessment boundary: Assessment is limited to analysis of the following properties: density, melting point, boiling point, solubility, flammability, and odor.]

  MS-PS1-3

  Gather and make sense of information to describe that synthetic materials come from natural resources and impact society. [Clarification Statement: Emphasis is on natural resources that undergo a chemical process to form the synthetic material. Examples of new materials could include new medicine, foods, and alternative fuels.] [Assessment Boundary: Assessment is limited to qualitative information.]

  MS-PS1-6

  Undertake a design project to construct, test, and modify a device that either releases or absorbs thermal energy by chemical processes.* [Clarification Statement: Emphasis is on the design, controlling the transfer of energy to the environment, and modification of a device using factors such as type and concentration of a substance. Examples of designs could involve chemical reactions such as dissolving ammonium chloride or calcium chloride.] [Assessment Boundary: Assessment is limited to the criteria of amount, time, and temperature of substance in testing the device.]

• Inquiry Scale
  • Each lesson in the unit has an Inquiry Scale that provides directions on how to implement the lesson at the level that works best for you and your students.
  • “Level 1” is the most teacher-driven, and recommended for students in 4th-5th grades. “Level 4” is the most student-driven, and recommended for students in 7th-8th grades.
  • For differentiation within the same grade or class, use different inquiry levels for different groups of students who may require additional support or an extra challenge.
• Common Misconceptions
  • Students often think that molecules disappear when a substance changes to something they cannot see. Emphases to students that molecules are either physically changing state into a gas or being rearranged into a new and different molecule. This is known as the Law of Conservation of Matter.
  • Students often think of boiling as a chemical interaction because bubbling is occurring, despite the fact that it is a physical interaction. Emphasize to students that when water boils, the molecule involved does not change (Ex: water molecules in liquid water are much closer together than the water molecules in vapor), whereas in a chemical interaction, bubbling is due to a new gas being made by rearranging bonds in molecules.
  • Students often use the word “reaction” for both chemical and physical interactions. Rather, we use the term “chemical reaction” to explain when substances are actually chemically changing from one form to another, whereas we use the term “physical change” when substances are merely changing shape or state.
  • Dissolving salt in water is a chemical change because the original structure of the salt “molecule” does not exist any more, rather, the sodium and chlorine separate to form ions, changing the molecular structure.
• Vocabulary
  • • Molecule
    • Chemical Reaction
    • Physical Change
    • Reactant
    • Product
    • Reversible
• Leveled Reading

  * To give our users the most comprehensive science resource, Mosa Mack is piloting a partnership with RocketLit, a provider of leveled science articles.

  • Make Something New!
    
    In this article, students read about the different ways we can put matter together to make what we see around us. They will read about using a chemical equation to see which atoms turn into different compounds and how matter in conserved in chemical reactions.

  
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  • If I Freeze or Boil You, You Won't Change?
    
    In this article, students read about the difference between a chemical change and a physical change. They learn that in a physical change, a substance will change the way it looks, but this won't change what it is.

  
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  • How to Make a Model Volcano
    
    This article looks at one of the most common chemical reactions that students may observe in a science lab. Students will read about the common and chemical names for baking soda and vinegar, as well as unstable carbonic acid as the first product and the final products of water, CO2 and salt.

  
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  • Nothing Lost, Nothing Gained
    
    In this article, students read about the idea that chemical reactions involve equal amount of products and reactants. We can use a chemical equation to see what all the different parts of the reactant turned into after the reaction.

  
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  • Putting Away the World's Blocks
    
    In this article, we explain how elements are sorted in the periodic table and how their physical properties can change without any change in their chemical properties.

  
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