How to Teach the Changes in States of Matter to Middle School Science Students

Maybe you’re facing a classroom full of middle school science students and you’re ready to teach the changes in states of matter (also called phase changes). Or maybe you’re a parent or caregiver who is looking to provide extra science support or a homeschooling science unit for your child. This blog post is designed to walk you through an age-appropriate unit on the changes in states of matter so you can successfully teach your 5th, 6th, 7th, or 8th grade science student(s). 

What are the changes in states of matter?

When matter moves from one state to another it is called a change in state of matter or a phase change. Changes in state happen when the energy level increases or decreases. This can happen when the temperature goes up or down or when the amount of pressure on an object changes. Changes in states of matter are physical changes. The changes in states of matter include melting, freezing, vaporization, condensation, sublimation, and deposition.

What prior knowledge do students need to have before beginning a unit on the changes in states of matter?

To understand the changes in states of matter, students need to understand the definitions of matter, mass, and volume. Even more importantly, they need to understand the particle movement and defining characteristics of solids, liquids, and gases. Here are the key things students need to know about each of these states of matter.

• Solids have a definite shape and a definite volume. That means they keep their shape and size regardless of where they are located. The particles in a solid are closely packed in a fixed position, which is why solids have a definite shape and volume. The particles in a solid vibrate but do not move around from place to place. 
• A liquid has a definite volume but does not have a definite shape. That means liquids take up a set amount of space but do not have a shape of their own—they either spread into a puddle or take the shape of their container. The particles in a liquid are closely packed. They vibrate, move around, and slide past each other.
• A gas does not have a definite shape or a definite volume. This means the size and shape of a gas can change. Gas particles can spread out far and wide or squeeze tightly together to fill a container. The particles in a gas vibrate and move freely at high speeds. 

Middle school students should already be familiar with the information about solids, liquids, and gases bulleted above. However, due to a whole host of circumstances, this isn’t usually the case. If you’re fairly certain you have a group of unicorn students who already know all there is to know about the states of matter, give them a quick states of matter preassessment. If they do well on the preassessment, then you know they’re ready to get down to business with melting, freezing, vaporization, condensation, sublimation, and deposition. 

If your students are ponies instead of unicorns, read the next section for what you can do to learn or refresh those building blocks of states of matter information. 

How can I teach or review the states of matter?

A direct way to review or teach the basics is to provide a States of Matter Informational Text Reading Comprehension Passage and Worksheet. Sometimes that's all your students need to be refreshed and ready to rock. 

For your more movement-oriented students, you can do hand motions for each of the states of matter. A solid can be modeled with a student's fists pressed together at the wrists, gently vibrating and tapping each other. A liquid can be modeled with a student's fists doing close circles around each other. A gas can be modeled with a student's fists going way apart and coming back together and circling around and generally making a whole lot of movement. (Watch out classmates!)

Sometimes you need a practice assignment to reinforce the material. In that case, here are two easy-to-incorporate resources.

• The States of Matter Worksheet is a straightforward one-page assignment designed to review and practice the most important concepts.
• The Free States of Matter Odd One Out Worksheet is a critical thinking assignment that will challenge your students to dig deeper into the material and find similarities and differences between the three covered states of matter. It's awesome, and it's free. 

Assess whether or not your students are ready to get to the changes in states of matter by using the preassessment mentioned above as a States of Matter Quiz.

What do my students need to know about the changes in states of matter?

Here are some of the basics you will want to be sure to include in your changes in states of matter unit. You'll also want to include examples of each phase change.

• Changes in pressure and temperature can alter energy levels. The change in energy level can cause matter to change state.
• Melting is a change from a solid to a liquid. When something melts, the particles move faster and break free from their fixed positions. 
• Freezing is a change from a liquid to a solid. When freezing occurs, the particles in a liquid slow down enough to form regular patterns. 
• Vaporization is a change from a liquid to a gas. The particles in a liquid gain enough energy to form a gas. Boiling and evaporation are both types of vaporization, but they have key differences. Boiling occurs throughout the liquid and happens quickly. Evaporation takes place only on the surface of a liquid and is a slower process.
• Condensation is a change from a gas to a liquid. Condensation happens when the particles in a gas lose enough energy to form a liquid. 
• Sublimation is a change from a solid to a gas. Sublimation happens when the particles in a solid gain enough energy to form a gas. The liquid state is skipped in this change. 
• Deposition is a change from a gas to a solid. Deposition happens when the particles in a gas lose enough energy to form a solid. The liquid state is skipped in this change. 

I'm ready. My students are ready. How do I introduce the changes in states of matter?

To begin your unit on phase changes you need to introduce the new material (the information in the bulleted points in the section above). Depending on your style and your students needs, you can do this via video, interactive notebook pages, PowerPoint or Google Slides, or a Changes in States of Matter Reading Comprehension Passage.

I personally prefer to begin with a combination of PowerPoint, lecture, and interactive notebook pages. I've used this Changes in States of Matter Interactive Notebook and PowerPoint set with my students for years. Read about setting up and using interactive notebooks in your classroom.

Once you have introduced the changes in states of matter content, your students will need a LOT of practice to reinforce and absorb it all.

I need a change in states of matter worksheet. What's out there?

I think worksheets have a place in education, especially if they aren't the typical boring ones you know you did but can't remember from your childhood. Here's a list of changes in states of matter worksheets you may want to incorporate into your unit.

• This Changes in States of Matter Worksheet is two pages long and is composed of three different sections that hit on different styles of learning and understanding.
• The Changes in States of Matter Odd One Out is a critical thinking assignment that will really challenge your students' understanding. I LOVE Odd One Outs, and, honestly, my students do, too. They're more like a puzzle or game than a worksheet, and they promote great student discussions. Here's information about using Odd One Out style questions in all subjects.
• The Changes in States of Matter Coloring Worksheet is fun because it has coloring, but it also asks students important "How do you know that's the right answer?" kind of questions. 

I think worksheets are lame. What changes in states of matter ACTIVITIES can I use?

Yes, it's science. Let's do the fun stuff. Here's a list of activities you can include in your changes in states of matter unit. 

• Here is a detailed blog post with directions for a changes in states of matter experiment or demonstration you can do with your students. It has minimal (and easy-to-find!) supplies. Personally, I did this as a demonstration instead of a hand-on experiment because it involves boiling water and my seventh graders weren't always the most cautious or safety-minded. 
• Are you familiar with Boom Learning? If you care, here are some Changes in States of Matter Digital Task Cards you can use on the Boom website.
• Stations! My students and I love stations! Use this set of 22 Changes in States of Matter Stations to practice the material of this unit. If you've never used stations, or never used them successfully, please read this information to make stations run smoothly in even your wildest classroom.
• A Changes in States of Matter Card Sorting Activity is a fun and easy way for students to interact with the material. Going beyond sorting definitions and examples and particle drawings, have your students explain how each card represents its specific change in state of matter.

How do I wrap up my changes in states of matter unit?

Two ways you can conclude your phase change unit are a traditional written assessment or a creative project (or both).

• If you are short on time or just prefer a written assessment, you can use this quick Changes in States of Matter Assessment.
• If you have more time and/or like to mix some creativity into your science classroom, you can wrap things up with a student project. I like to give my seventh grade students the option of creating a Changes in States of Matter Poster or a Changes in States of Matter Comic.

I'm a classroom teacher. Is there a way to bundle the resources mentioned in this blog so I can save some dough?

Yes, you can get these resources in two different money-saving ways.

• The Changes in States of Matter Bundle is heavily discounted and contains many of the resources mentioned in this blog post.
• I offer Custom Bundles in my TPT store, where you can build your own bundle of the resources of your choosing. The number of resources you select determines whether you save 20%, 25%, or 30%.

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I need resources for homeschooling. Do you have anything specifically for students learning outside of a traditional classroom environment?

Yes! I published my Changes in States of Matter Workbook on Amazon. It is an entire homeschooling science unit designed with 5th, 6th, 7th, and 8th grade students in mind. Learn more about my workbook in this blog post. 

Read Cathy Duffy's thorough review of my Changes in States of Matter Workbook and also my Physical and Chemical Changes Workbook.