5-PS1-1: Matter Made of Tiny Particles
Also called NGSS 5-PS1-1 · Topic: Structure and Properties of Matter · Physical Science
The Official Wording
Develop a model to describe that matter is made of particles too small to be seen.
Clarification statement: Examples of evidence supporting a model could include adding air to expand a basketball, compressing air in a syringe, dissolving sugar in water, and evaporating salt water.
Assessment boundary: Assessment does not include the atomic-scale mechanism of evaporation and condensation or defining the unseen particles.
NGSS Lead States, 2013 · Read it on nextgenscience.org · checked October 15, 2026
What 5-PS1-1 Means in Plain English
Fifth graders build a model showing that every kind of matter, even air, is made of pieces far too small to see. They use evidence like squeezing air in a syringe, pumping up a ball, or watching sugar seem to disappear in water, and explain it with particles.
Students do not need to name the particles as atoms or molecules, and they do not explain evaporation at the particle level. This builds on 2-PS1-1, where they described materials by their properties, and leads to atoms and molecules in MS-PS1-1.
5-PS1-1 I Can Statements
- I can explain that air and water are built from tiny particles.
- I can use a model to show why air squeezes into less space.
- I can use particles to explain where dissolved sugar goes.
5-PS1-1 Worked Example
A particle test a class can run at their desks with two plastic syringes and a cup of water.
Why can we squeeze the air in a syringe but not the water?
Set It Up: Two plastic syringes without needles, a cup of water, and a fingertip or cap to seal each tip.
- Pull the plunger of the first syringe back to the 10 mL mark, then seal the tip.10 mL of air, sealed
- Push the plunger in as hard as you safely can and read the mark.Air squeezes to about 5 mL
- Let go and watch the plunger.It springs back toward 10 mL
- Fill the second syringe with 10 mL of water, seal it, and push again.Water barely moves from 10 mL
- Draw what is inside each syringe as dots, before and after the push.Air dots spread out, water dots packed
The air shrank to about half its space and sprang back, while the water would not squeeze at all.
Why it works: Air is made of tiny particles with lots of empty space between them, so pushing crowds them closer, but water particles are already packed tight.
Common Mistakes with 5-PS1-1
Thinking air is nothing
“The syringe is empty, there's nothing in it.”
Try this: Seal the tip and push the plunger. Something pushes back, so the syringe is full of air particles you cannot see.
Saying the sugar melted or vanished
“The sugar melted and now it's gone.”
Try this: The sugar split into particles too small to see and spread through the water. Let the water dry up and the crystals come back.
Drawing particles that shrink
Smaller dots drawn after the air is squeezed
Try this: The particles stay the same size. Squeezing only moves them closer together, so draw the same dots with less space between them.
Where 5-PS1-1 Fits
Practice 5-PS1-1
Quick Check
- A balloon gets bigger when you blow into it. What did you add?
- Salt stirred into water disappears. How could you show it is still there?
- Why does a sealed syringe of air push back when you squeeze it?