What is matter?

Author(s): SEP staff

Lesson Overview

Grade level(s):

Elementary School (K-5), Middle School (6-8), High School (9-12), Grade 3, Grade 4, Grade 5, Grade 6, Grade 7, Grade 8, Grade 9


Chemistry, Physical Science



Big ideas(s):

Chemistry is the study of matter.
Matter has three forms: Solid, liquid or gas.
Matter is everything that takes up space and has mass.
All matter is madeup of small particles (atoms).

Vocabulary words:

matter, energy, force, volume, mass

What you need:

  • SEP Kit What is matter? K172 (Upper grades), K233 (Lower grades) or K235 (bilingual Engl/Span.), containing cards with various "items" printed on them
    If you don't have access to the SEP Resource Center you can make your own set of cards using the attached item labels


Students work in pairs during the sorting the cards part of this activity and then come together as a whole class to discuss their choices and create a definition of matter.



Time needed:

Sorting activity: 20 minutes
Discussion and creating a definition: 20-30 minutes

Author Name(s): 
SEP staff

This activity is based on a lesson from the Living by Chemistry curriculum developed by the Lawrence Hall of Science (see citation).

During this activity students explore in depth their own understanding of what constitutes "matter" and work together as a group to create a definition for matter.

Students work in pairs to debate how to sort "items" printed on cards into three categories: "matter", "non-matter" and "unsure" and then try to determine what properties all items in each category have in common. A whole class discussion about "tricky" items follows during which students ultimately agree on a definition of matter.

You can choose which cards you would like to use depending on your students' age, abilities, and experiences.  As an example, for elementary grades, you might choose not to use the entire set.

Learning goals/objectives for students: 

Students will be able to define matter and give examples for matter and non-matter.

Content background for instructor: 

This is a great activity to assess students' prior knowledge and misconceptions about matter.
Sorting the items into matter or non-matter will most likely result in a rich discussion full of controversies and intriguing questions.

Some of the items are meant to be thought provoking:

  • Wind can be felt on your skin and you can see the wind move branches of trees. But wind itself it not matter. It is the movement of air, which itself is matter.
  • Electricity is similar. You can see the result of electricity at work - a light bulb lighting up for example and you can feel electricity  as an electric shock. But electricity is just the the movement/flow of an electric charge - it is not matter itself. It is the movement of matter (electrons).
  • Sound is the result of air movement against your eardrum and not matter itself.
  • A flame or fire can also pose difficulties. The smoke that rises up from the fire or flame contains vaporized gases and small particles and therefore contains matter. But the fire and flame themselves, the light and heat emitted, are energy, not matter.

    The concept of energy is very abstract and can be pretty hard for students to grasp - especially younger ones. Energy is the ability or capacity to do work or supply heat.

When discussing what all items in the matter category have in common, some students might say that all matter can be detected with one of our senses. Challenge students to notice that a lot of items that are matter cannot be seen - at least with the naked eye (atoms, DNA, bacteria, dissolved sugar) and that some items that are non-matter can be felt (heat, wind, electricity).

Some common textbook definitions of matter are:

  • Matter is anything that takes up space and has mass.
  • Matter has mass and volume.

Students might challenge those definitions, arguing that air (or gases in general) does not have mass (which they do). This is a great way to tie in an exploration where students try to design an experiment to find out whether air/gas has mass or not.

Getting ready: 
  • Check out What is matter kit from the SEP resource center or make your own set of cards using the attachment. If you make the cards yourself, printing the item names on address labels and sticking them on index cards works well

Lesson Implementation / Outline

  • Have students reflect on what they already know about matter by having them respond in their journals to the following questions:
    "What is matter? Give two examples of matter and two examples of non-matter."
    OR "Solids, liquids and gases each have measurable mass. What parts of this statement do you agree with? Disagree? Explain your answer in detail."
  • Introduce the activity to the students:
    1. If chemistry is the study of matter then to understand chemistry they must first understand what matter is. Through this activity students will collectively define  matter.
    2. By defining the term as a group, students will start to develop into a community of scientists. Science has its own language, but this language is built, collectively by the practicing community of scientists who agree on definitions for the terms they are using.
  • Explain the activity:
    1. Each pair will receive a set of “items”. The students' task is to work together and discuss whether each item is or is not matter. Ask students to discuss why they think the item is or is not matter and to challenge each others' thinking.
    2. Have students create a table to categorize their items:  Matter, not matter or unsure
    3. Based on their categorizations, ask students to come up with properties the things in the matter category have in common (and that apply to all matter).  Ask students to make a list of these properties. What about things that are not matter or that they are unsure about?
  • Have students report out
    Stress that the following two big ideas are critical to this and other report-outs:
    • Constructing an argument and defending a position – as students share their conclusions with the class, challenge them to explain why they made that decision. What evidence do they have?
    • Thinking critically and being skeptical. Explain that you want them to be working as a community and to really push all of their thinking. Encourage students to direct their report-out to the group, not to the teacher. Encourage students to ask one another questions.
    1. Ask a team to get the class started on this report out. Perhaps by sharing what item had the most interesting discussion for their pair. Why? And what does this tell us about matter? Leave this discussion solely student-centered at this time. Have pairs report out, challenge and question each other, share their difficulties categorizing certain item etc. Refrain from judging, correcting or giving the "right" answer. Instead, probe students' ideas by asking "Did anyone else have trouble categorizing this item? Why?". "How did other pairs categorize this item? Why?". Highlight students' confusions, difficulties and controversies.
    2. After all "tricky" items have been discussed (see Instructor background section above), ask students to share if they were able to find common characteristics of items in the matter category as well as of items in the non-matter category. Ask students: "If something is not matter - what is it?"
    3. Collect responses about characteristics of matter/non-matter on blackboard/overhead while students report out. Again, don't comment just yet - just record. Challenge students' responses by asking the class "Does everyone agree with this?," "Is that characteristic true for all items in the matter category?" etc.
    4. Add and cross out characteristics of matter until all students agree that ALL matter shares those common characteristics.
    5. Based on that list of characteristics, ask students to create a definition of matter that everybody can agree on. Write down the definition on a wordwall or large poster to refer back to during later lessons.
    6. Share some textbook defintions of matter and have students compare these definitions to theirs. Are those definitions useful for them? Do they give them any more insights?
Checking for student understanding: 
  • While students work in pairs, sorting the items, walk around, listen in on their discussions and ask probing questions to get a sense of students' understanding of matter.
  • The discussion of students' placement of items will reveal students' misconceptions and internal struggles about the concept of matter.
  • The pre-activity journal reflection can be repeated at the end of the class to determine how students' ideas might have changed.
Wrap-up / Closure: 

Have students repeat their pre-activity journal reflection at the end of the class to determine how students' ideas might have changed.

Extensions and Reflections

Extensions and connections: 

Lessons dealing with the different states of matter, changes in the state of matter, investigations determining whether all matter truely has mass and volume, can follow this lesson. Important science skills such as measuring mass and volumes of liquids, gases and regular and irregular solids can be tied in as well.


Trying to sort the cards into matter or non-matter items sounds easy - but it is not. Even adults can struggle with a lot of the tricky items. SEP does this activity during the Chemistry of Life summer course with teachers and it regulary sparks interesting discussions full of controversies.

What is matter items.doc41.5 KB
What is matter items english_spanish.doc45.5 KB
What is matter student task card.doc25 KB
NGSS Topics
Kindergarten through Grade 5: 
Middle School (6-8) Physical Sciences: 
High School (9-12) Physical Sciences: 
NGSS Disciplinary Core Ideas
Middle School (6-8): 
High School (9-12): 
NGSS Performance Expectations
NGSS Performance Expectations: 
NGSS Science and Engineering Practices
NGSS Crosscutting Concepts
NGSS Crosscutting Concepts: 

Standards - Grade 3

Physical Sciences: 
1. Energy and matter have multiple forms and can be changed from one form to another. As a basis for understanding this concept:
e. Students know matter has three forms: solid, liquid, and gas.
h. Students know all matter is made of small particles called atoms, too small to see with the naked eye.

Standards - Grade 4

Physical Sciences: 
1. Electricity and magnetism are related effects that have many useful applications in everyday life. As a basis for understanding this concept:
g. Students know electrical energy can be converted to heat, light, and motion.

Standards - Grade 5

Physical Sciences: 
1. Elements and their combinations account for all the varied types of matter in the world. As a basis for understanding this concept:
b. Students know all matter is made of atoms, which may combine to form molecules.
Investigation and Experimentation: 
6. Scientific progress is made by asking meaningful questions and conducting careful investigations. As a basis for understanding this concept and addressing the content in the other three strands, students should develop their own questions and perform investigations. Students will:
a. Classify objects (e.g., rocks, plants, leaves) in accordance with appropriate criteria.

Standards - Grade 6

Physical Sciences: 
3. Heat moves in a predictable flow from warmer objects to cooler objects until all the objects are at the same temperature. As a basis for understanding this concept:
a. Students know energy can be carried from one place to another by heat flow or by waves, including water, light and sound waves, or by moving objects.
Investigation and Experimentation: 
7. Scientific progress is made by asking meaningful questions and conducting careful investigations. As a basis for understanding this concept and addressing the content in the other three strands, students should develop their own questions and perform investigations. Students will:
e. Recognize whether evidence is consistent with a proposed explanation.

Standards - Grade 8

Structure of Matter: 
3. Each of the more than 100 elements of matter has distinct properties and a distinct atomic structure. All forms of matter are composed of one or more of the elements. As a basis for understanding this concept:
d. Students know the states of matter (solid, liquid, gas) depend on molecular motion.

Standards - Grades 9-12 Investigation and Experimentation

Investigation and Experimentation: 
d. Formulate explanations by using logic and evidence.
l. Analyze situations and solve problems that require combining and applying concepts from more than one area of science.