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NESA Accredited Teacher
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High school chemistry & physics specialist 30+ years
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The Crazy Scientist in primary schools — 15 years
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International conference presenter on science education
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Creator of the LAB™ Learning System
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Curriculum aligned: NSW Science & Technology K–6 (2024)
A picture is worth a thousand words — check this out and see if you can spot the science hiding in plain sight.
From the LAB
What you will need
100mL shampoo
4 sheets of toilet paper — standard 2-ply
A mixing bowl
A spoon
Food colouring — optional; add to shampoo before mixing
A refrigerator
For Variable 2: 2–3 different shampoo brands
The ingredient label from each shampoo bottle — or a photo of it
How to do it
1
Mix the shampoo
Measure 100mL of shampoo into your mixing bowl. Add food colouring now if using.
Stir vigorously for 1 to 2 minutes — you want to aerate the shampoo so it becomes slightly lighter and fluffier.
This distributes the polymer chains through the mixture and gives them room to form a network.
3
The fridge test
Divide your mixture into two equal portions. Place both in sealed containers or cover them with cling wrap.
Put one portion in the fridge and leave the other on the bench at room temperature.
Note the time. Leave both for 2 hours — do not mix or disturb them during this time.
While you wait, record a prediction: will the fridge version be stretchier, firmer, or the same as the room temperature version?
5
Shampoo test
Now repeat Steps 1 to 5 using a different shampoo brand. Read that label first — does it contain carbomer?
Where does it appear in the list compared to your first shampoo?
Run exactly the same method and the same three tests. Compare the results
2
Add the toilet paper
Tear 4 sheets of toilet paper into small pieces and add them gradually to the shampoo.
Stir as you go until the paper is fully incorporated and no dry pieces remain.
The mixture will look lumpy and uneven at first — keep mixing until it becomes more uniform. Describe the texture now: does it already feel like slime, or is it too wet and loose?
4
Testing slimes
After 2 hours, take the fridge portion out and let it sit for 2 minutes. Then mix both portions vigorously for 1 minute.
Now run the same three tests on each:
the stretch test (pull slowly between both hands — how far does it go before breaking?),
the pressure test (press slowly then press quickly — does it behave differently?), and the
bubble test (look closely at the surface — can you see bubbles, or is the structure smooth and continuous?).
Record your observations for both versions side by side.
6
What did you find out?
Based on both variables — fridge vs no fridge, and shampoo A vs shampoo B — write a single sentence that summarises what actually controls the result.
Did it work? Share the science! Tag @the_crazy_scientist on Instagram — we love seeing your experiments!
Sick Shampoo Slime
Designed by Darin Carr (BSc, DipEd)
NESA Accredited Teacher Chemistry & Physics Specialist
Creator of the LAB™ Learning System
No glue. No borax. Just shampoo, toilet paper, and a question worth answering: does the brand matter?
5-12 yrs
Easy
120
min
Stage 2, Stage 3
>
Sick Shampoo Slime
The Crazy Scientist LAB Learning System™
Every experiment follows The Crazy Scientist Lab Learning System™ — a simple way to help kids think like real scientists.
We
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LINK to what they already know,
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ACTIVATE curiosity through hands-on discovery
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BUILD understanding that actually sticks.
This recipe has been viewed tens of millions of times online — and almost every version gives a different result. Same ingredients listed, completely different outcomes.
The reason is in the fine print. Shampoo is not a single ingredient — it is a mixture of surfactants, conditioning agents, fragrances, and polymers. And not all shampoos have the same ones.
Before you make anything today, you are going to read the label and make a prediction. What ingredient do you think is responsible for the stretchy result — and how could you test whether you are right?
Then make it. Change one variable. And find out whether the label told the truth.
Which shampoo produced the better result — and where did carbomer appear in its ingredient list compared to the other brand?
The fridge version and the room temperature version had the same ingredients, the same method, and the same waiting time. If one was better, what did the cold actually do to the polymer network?
Toilet paper is made of cellulose — the same class of molecule as psyllium husk. But cellulose from toilet paper is not cross-linked the way PVA slime is. What does that mean for how the slime holds together — and why might it feel different from PVA slime even if it stretches?
If you were going to write a better version of this recipe for someone who had never made it before, what would you add to the instructions that most online versions leave out?
Carbomer is used in face creams, sunscreens, hand sanitisers, and hair gels — anywhere a product needs to be thick and smooth without feeling greasy. What property of carbomer makes it useful across all of those products — and is it the same property that made your slime stretchy?
Ingredient lists on cosmetic products are required by law to list ingredients from highest to lowest concentration. If carbomer appears near the bottom, it is present in a very small amount.
Does a smaller amount of carbomer always mean a worse slime — or could other ingredients also contribute? How would you design a test to find out?
The cellulose from toilet paper forms hydrogen bonds when wet, which helps the mixture hold together. Psyllium husk is also a cellulose-based polysaccharide that holds water. If you replaced the toilet paper with psyllium husk powder, what do you predict would happen — and what would you need to test to find out?
"Want the full teacher guide? The Crazy Scientist Lab includes classroom delivery tips, how to manage the WOW moment, differentiation for Stage 2 & 3, — ready to teach tomorrow."
Think Like a Scientist
Scientists don't just do ONE experiment; they change one part of the experiment (independent variable) and then see how it affects another part of the experiment
(dependent variable)
Change ONE variable and test again.
Does refrigerating the mixture change the result — does the fridge version produce a firmer, stretchier slime than one left at room temperature for the same time, or does temperature make no measurable difference?
Does the shampoo brand change the result — does a shampoo with carbomer on the ingredient list produce a better slime than one without it, and can the ingredient list predict the outcome before you test?
🧪 Try it! Change ONE thing and test again. What did you discover?
Want to go deeper? Tap a section below to explore. ▼
The Science Behind It
What's really making it stretchy?
Shampoo isn't just liquid soap. It's a mixture of different ingredients — cleaners, conditioners, perfumes, and thickeners.\
The thickener is the key ingredient here. Many shampoos contain a thickening ingredient called carbomer, which is a long, springy molecule that makes the shampoo feel thick and smooth.
When those long molecules mix with water, they tangle together and form a kind of gel. When you add toilet paper, you're adding tiny plant fibres from the wood pulp it's made from.
Those fibres weave through the gel and hold it together — a bit like adding straw to mud bricks to stop them crumbling. That combination of gel and fibres is what gives the slime its stretch. The stretch comes from the shampoo, not the toilet paper.
Why the label predicts the outcome?
Not all shampoos have the same amount of carbomer — and that's exactly why some make great slime and others barely gel at all. By law, cosmetic products must list their ingredients in order from the most to the least. If carbomer is near the top of the list, there's a lot of it.
Near the bottom means very little. The recipe is exactly the same. The ingredient is different. That's why reading the label before you start isn't just following instructions — it's making a real scientific prediction about what will happen.
Why the fridge makes a difference?
Cold temperatures slow everything down, including the tiny moving parts inside your mixture. When it sits in the fridge, the long carbomer molecules have time to settle and organise themselves properly, and the plant fibres from the toilet paper have time to soak up water and swell slightly.
At room temperature, everything is still moving too fast to settle. Two hours in the fridge gives the mixture time to form a proper structure — which is why the chilled version comes out firmer and stretchier than the room-temperature one.
Real-world connection
Carbomer shows up in products you probably use every day — hand sanitiser, sunscreen, face cream, and eye drops. In every case it's doing the same job: creating a thick, smooth gel that's easy to spread and holds its shape.
The slime you made today uses the same chemistry that scientists use when they design those products. And the prediction trick — reading an ingredient list to guess what a product will do — is exactly what professional product designers use when they're developing new formulas.
Try next
Compare the plant-fibre stretch to a slime made entirely from natural plant gel → [Snail Slime]
Explore a slime made by linking molecules together with a chemical activator → [The Polymer Factory]
Extension: G&T Years 5 & 6
What is a polymer?
The key ingredient in this experiment — carbomer — is a synthetic polymer. The word polymer comes from Greek: poly (many) + meros (parts).
A polymer is a very long molecule made by linking thousands of smaller identical units together in a chain. Imagine linking hundreds of paper clips into one long chain — that is the basic idea.
Natural polymers include rubber, cellulose from plants, and the DNA inside every living cell. Synthetic polymers include plastic, nylon, and carbomer.
Toilet paper is made from cellulose — a natural polymer from wood pulp. The shampoo contains carbomer — a synthetic polymer. Both end up in your slime. What do you think each polymer contributes to the final result — and how could you test which one is responsible for the stretch?
Vocabulary
Polymer
A very long molecule made by linking thousands of smaller identical units in a chain. Examples include carbomer, cellulose, nylon, and rubber.
Carbomer
A thickening ingredient found in many shampoos, creams, and gels. It forms long, springy molecules that create a smooth, stretchy gel when mixed with water.
Surfactant
An ingredient in shampoo that does the cleaning. It attaches to both water and grease at the same time, so that oil and dirt can be rinsed away.
Cellulose
A natural material found in plant cell walls and wood pulp. Toilet paper is made of cellulose fibres, which weave into the slime gel and help hold it together.
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Perfect for classroom libraries or home explorations.
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