Unit Overview

In this unit about states of matter, learners help Mosa clear her name after a court of birds accuses humans of messing with the level of their local lake. Through this video mystery as well as a hands-on modeling activity, learners will discover that gases, liquids, and solids all consist of particles that behave differently in different states. After learners explore these properties in a lab setting, they will use their knowledge of states of matter to design a solution to a critical problem in the city of Particleville.

Lesson Overview

Medium solveSolve: Missing Water Mystery + Vocabulary Mind Map
Medium makeMake: Lab Stations: Experience States of Matter
Medium engineerEngineer: Use States of Matter Knowledge to Solve a Problem in Particleville

Learners help Mosa solve the mystery of why the lake changes levels throughout the year. Utilizing new vocabulary and guided video questions, learners eventually discover that even though a substance may be made up of the same atoms, it has different properties in solid, liquid, and gas form. (80 minutes)

Learners explore the different states of matter through a series of lab stations, making observations and coming to conclusions about what their observations mean for particle motion in different states. (100 minutes)

The city of Particleville is having some problems: excessive potholes, a desperate demand for fresh water, and a tired balloon artist who needs help blowing up all his balloons! Building off what they learned in the “Make” and the “Solve,” learners design a solution to one of Particleville’s problems. (150 minutes)

Next Generations Science Standards

Develop a model that predicts and describes changes in particle motion, temperature, and state of a pure substance when thermal energy is added or removed. [Clarification Statement: Emphasis is on qualitative molecular level models of solids, liquids, and gases to show that adding or removing thermal energy increases or decreases kinetic energy of the particles until a change of state occurs. Examples of models could include drawing and diagrams. Examples of particles could include molecules or inert atoms. Examples of pure substances could include water, carbon dioxide, and helium.]

Science & Engineering Practices

  • Developing and Using Models

Disciplinary Core Ideas

  • Definitions of Energy
  • Structure and Properties of Matter

Cross Cutting Concepts

  • Cause and Effect

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

  • Learners often confuse an increase in particle motion with simply having fewer molecules (more space to move).
  • Learners initially think that a solid, liquid, and gas are completely different substances when in fact they have the same molecular composition.
  • Learners often think that the molecules themselves are expanding or contracting depending on their state, when it is really the substance that expands or contracts due to the motion of molecules.


    • State
    • Liquid
    • Solid
    • Gas
    • Melt
    • Freeze
    • Evaporate

Content Expert Title

  • Hans C. von Baeyer
    Chancellor Professor of Physics, Emeritus College of William and Mary


  • 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.

  • Gas - The Crazy Kids

    Medium 177 617
    In this article, students will explore the properties of gases. They will look how these molecules independently move and collide. The article also discusses how volume and pressure in a gas can change.

  • Matter Changes

    Medium 166 606
    With a little more or a little less heat, everything can change. In this article, we explore how heat changes matter from solid, liquid, gas, and plasma.

  • It's Not Magic . . . It's Just a Phase

    Medium 176 616
    In this article, students investigate the concepts of freezing point, boiling point, and melting point through a magic trick. They'll read about how a magician makes water change phase through heating and cooling at each of these temperatures.

  • 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.

  • Solid!

    Medium 173 613
    This article explores the formation and structure of a solid. Students will look at the concept of a repeating pattern and the lattices that hold together all of the building blocks that make up a solid.

  • Waiting For Water

    Medium 179 619
    In this article, students read about the basics of fluids and their behaviors. They read about the basics of flow, fluid, condensation and the attractive forces that hold things together in liquids and solids.