Grade 4
The Human Knowledge Project
Unit 11 — Matter and Energy
Welcome to Grade 4 Science!
Everything around us is made of matter.
Matter can change, move, and interact with energy in many different ways.
Scientists study matter and energy to understand how the physical world works.
Today you will begin exploring these important ideas.
What Is Matter?
Matter is anything that has:
- mass
- volume (takes up space)
Examples of matter include:
- air
- water
- rocks
- trees
- animals
- people
Even though you cannot always see it, air is matter because it has mass and takes up space.
States of Matter
Matter exists in three common states.
Solid
A solid has:
- a definite shape
- a definite volume
Examples:
- rock
- book
- ice
Liquid
A liquid has:
- no definite shape
- a definite volume
Liquids take the shape of their container.
Examples:
- water
- milk
- juice
Gas
A gas has:
- no definite shape
- no definite volume
Gases spread out to fill the space around them.
Examples:
- air
- oxygen
- water vapor
Physical Properties
Scientists describe matter by observing its physical properties.
Examples include:
- color
- size
- shape
- texture
- mass
- volume
- hardness
- flexibility
These properties help identify and compare different materials.
Physical Changes
Sometimes matter changes without becoming a new substance.
Examples include:
- melting ice
- freezing water
- tearing paper
- breaking glass
These are called physical changes.
The material remains the same substance even though its appearance changes.
Energy
Energy is the ability to do work or cause change.
Common forms of energy include:
- light
- heat
- sound
- electrical energy
- motion (kinetic energy)
Energy allows things to move, grow, and change.
Heat Energy
Heat moves from warmer objects to cooler objects.
Examples:
- a spoon becoming warm in hot soup
- ice melting in sunlight
- your hands warming near a campfire
Heat causes many changes in matter.
Observing Matter
Scientists carefully observe matter using:
- sight
- touch (when safe)
- measuring tools
- experiments
Good observations lead to better scientific understanding.
Activity
Collect five different objects.
For each object, record:
- solid, liquid, or gas
- color
- texture
- size
- mass (if possible)
Then explain one physical property that makes each object unique.
Practice
Answer these questions.
What is matter?
What are the three common states of matter?
How is a liquid different from a solid?
What is a physical property?
What is a physical change?
Name five forms of energy.
Review
Today you learned:
- matter has mass and takes up space
- matter exists as solids, liquids, and gases
- physical properties describe matter
- physical changes do not create new substances
- energy causes movement and change
- careful observation is an important scientific skill
Understanding matter and energy helps explain many of the changes we observe every day.
Looking Ahead
Next we will investigate electricity and magnetism, discovering how invisible forces power many of the technologies we use every day.