5-PS1-4: Does Mixing Make a New Substance?
Also called NGSS 5-PS1-4 · Topic: Structure and Properties of Matter · Physical Science
The Official Wording
Conduct an investigation to determine whether the mixing of two or more substances results in new substances.
NGSS Lead States, 2013 · Read it on nextgenscience.org · checked October 15, 2026
What 5-PS1-4 Means in Plain English
Fifth graders mix two or more substances and gather evidence about whether something new formed. They look for clues like a gas, a solid appearing in a liquid, a color change, or a temperature change, and compare the properties of the result with what they started with.
Students do not need atoms or chemical equations. They tell plain mixtures, like salt in water, apart from changes that make a new material. This builds on 2-PS1-4 and leads to MS-PS1-2, where properties are used to identify chemical reactions.
5-PS1-4 I Can Statements
- I can plan a test that mixes substances and watches for changes.
- I can name clues that a new substance has formed.
- I can tell a mixture from a change that makes something new.
5-PS1-4 Worked Example
A kitchen chemistry test with warm milk, lemon juice, salt, and a fine strainer.
Which mixture makes a new substance: salt in water, or lemon juice in warm milk?
Set It Up: A cup of warm milk, a cup of water, a spoonful of salt, two tablespoons of lemon juice, a fine strainer, and a small dish.
- Stir the salt into the cup of water and note what you see.Salt disappears, water stays clear
- Stir the lemon juice into the warm milk and wait two minutes.Lumpy white bits form
- Pour the milk mixture through the strainer.Soft curds stay behind, thin liquid drips through
- Leave a spoonful of the salt water in the dish for a few days.Salt crystals left in the dish
- Compare the curds with fresh milk and try stirring them back in.Curds stay firm and will not mix back
Salt in water was a mixture you could reverse, but lemon juice and milk made firm curds, a new substance.
Why it works: The acid in lemon juice changes the proteins in milk so they clump into a new material with different properties, while dissolved salt stays salt.
Common Mistakes with 5-PS1-4
Calling every change a new substance
“The salt is gone, so the water turned into something new.”
Try this: Dissolving makes a mixture. Dry out the water and the same salt returns, so nothing new was made in that cup.
Trusting one clue
“It changed color, so it's a new substance,” after adding food coloring
Try this: Food coloring changes color without making anything new. Look for properties that differ, like a solid that will not mix back in.
Skipping the comparison
Describing the curds without looking at plain milk
Try this: Keep a sample of each starting substance beside the result, and compare their properties side by side before deciding.
Where 5-PS1-4 Fits
Practice 5-PS1-4
Quick Check
- Sugar stirred into tea disappears. Is that a new substance?
- Name two clues that mixing made a new substance.
- Why do the curds show that something new formed?