Unit Overview

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

Lesson Overview

Medium solveSolve: Molecular Mystery + Vocabulary Mind Map
Medium makeMake: Lab Stations: Is it a Physical or Chemical Change?
Medium engineerEngineer: Solve an Environmental Problem caused by Physical or Chemical Changes.

Students contextualize chemical reaction vocabulary in a mind map before helping Mosa Mack solve the mystery of why some food can go back to its original form, but some cannot! By the end of The Solve, students learn that chemical reactions result in a change at the molecular level. (100 mins)

Gather and analyze evidence to determine whether a physical change or chemical reaction has occurred. (75 mins)

Students engineer a solution to an environmental pollution issue caused by either a physical change or chemical reaction near the edge of Toxic Town. (150 mins)

Next Generations Science Standards

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.]
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.]
Develop and use a model to describe how the total number of atoms does not change in a chemical reaction and thus mass is conserved. [Clarification Statement: Emphasis is on law of conservation of matter and on physical models or drawings, including digital forms, that represent atoms.] [Assessment Boundary: Assessment does not include the use of atomic masses, balancing symbolic equations, or intermolecular forces.]

Science & Engineering Practices

  • Analyzing and Interpreting Data
  • Connections to Nature of Science
  • Planning and Carrying Out Investigations
  • Scientific Knowledge is Based on Empirical Evidence

Disciplinary Core Ideas

  • Chemical Reactions
  • Structure and Properties of Matter

Cross Cutting Concepts

  • Cause and Effect
  • Patterns

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.


    • Molecule
    • Chemical Reaction
    • Physical Change
    • Reactant
    • Product
    • Reversible


  • Powerpoints for Make and Design
  • Vocabulary Cards
  • Solve Student Handout
  • Make Student Handout
  • Design Student Handout
  • Vocabulary Mind Map

New: RocketLit 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!

    Medium 201 694
    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.

  • If I Freeze or Boil You, You Won't Change?

    Medium 204 697
    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.

  • How to Make a Model Volcano

    Medium 202 695
    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.

  • Nothing Lost, Nothing Gained

    Medium 207 700
    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.

  • Putting Away the World's Blocks

    Medium 181 627
    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.