The Petal Lab
Essy
Mission Briefing.
Pick any petal — any colour, any flower. Crush it, dissolve the pigments in rubbing alcohol, and load the extract onto a strip of chromatography paper. What travels up the strip might not be what you expected.
7-12 yrs
25
min
Medium
Stage 3
Designed by Darin Carr (BSc, DipEd)
NESA Accredited Teacher · Chemistry & Physics Specialist · 30+ years in-class teaching
Creator of the LAB™ Learning System
Last updated: June 2026 ·
[Cite this resource ↗]
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The Petal Lab
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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.
Mission Equipment
Fresh flower petals
Rubbing alcohol / isopropyl alcohol
A mortar and pestle
A small glass jar or cup
A pipette or dropper
Strips of chromatography paper
A pencil or chopstick
Tape
White paper or paper towel
Let’s Investigate
1
Choose your petal
Pick your petal — the more intensely coloured the better.
A deep red rose, bright orange marigold, or vivid purple pansy will give you richer, more visible results than a pale or white flower.
3
Add Alcohol
Scrape all the paste into your small jar.
Pour in just enough rubbing alcohol to completely cover the paste.
Give it a gentle swirl and leave it to sit for 5 minutes.
5
Build up the spot
Once the first spot is completely dry, load another small drop onto exactly the same point.
Let it dry again.
Repeat this process 3 to 4 times in total.
7
Read results
After 20 to 30 minutes, carefully remove the strip and lay it flat on white paper.
Count the colour bands.
How far did each one travel?
Are any of the bands a colour that wasn't visible in the original petal?
2
Crush the petal
Tear your petal into small pieces and place them in the mortar.
Use the pestle to grind them into a paste — keep going until you have a deeply coloured, almost liquid paste.
4
Load your first spot
After 15 minutes, use the pipette to draw up a small amount of the coloured extract.
Touch the tip to the base of your chromatography strip — about 1.5 cm from the bottom — and release one small drop onto the paper.
Let it dry completely before the next step.
6
Dip & Wait
Tape your loaded strip to a pencil and rest it across the top of the jar so only the very bottom of the strip just touches the alcohol — the pigment spot must stay above the liquid surface.
Leave it completely undisturbed for 20 to 30 minutes.
Did it work? Share the science! Tag @the_crazy_scientist on Instagram — we love seeing your experiments!
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.
You can see what colour your petal is just by looking at it.
But colour is just what your eyes detect — it doesn't tell you what's actually producing that colour inside the petal at the molecular level.
Here's your prediction before you start: pick up your petal and look at it carefully. How many different pigment molecules do you think are working together inside it to make that one colour you can see?
Write it down. One? Two? More? You're about to find out — and the answer is probably not what you'd guess from the outside.
How many bands appeared on your strip? Were any of them a colour you wouldn't have predicted from the original petal?
All the pigments started at exactly the same spot — why did they end up at different heights?
If someone else used a different-coloured petal, do your strips share any of the same bands?
Different pigments travel different distances because of their molecular size and how strongly they stick to the paper — this is called chromatography.
A food scientist suspects an orange drink contains undeclared dyes — how would chromatography help them check without tasting it?
Two flowers look identical in colour but came from different plants — could chromatography tell them apart? What would you be looking for?
If you ran this with a petal that's starting to wilt and turn brown — would you predict the same bands, fewer bands, or different ones entirely?
What other coloured liquids from everyday life do you think would separate into interesting bands on chromatography paper?
"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 the colour of the petal change how many bands appear — or how far the pigments travel up the strip?
Does the amount of alcohol used to cover the petal paste change how richly the extract is coloured — and does that affect the bands?
🧪 Try it! Change ONE thing and test again. What did you discover?
Dr Puddledrip’s Science Tip
Want to go deeper? Tap a section below to explore. ▼
The Science Behind It
The colour you see in a flower petal isn't painted on — it's produced by tiny molecules called pigments, packed inside the petal cells.
Different flowers use different types of pigments to make their colours. Reds, purples, and blues usually come from molecules called anthocyanins. Oranges and yellows come from carotenoids and flavonoids — the same pigment families hiding inside green leaves, revealed in [Sneaky Light Absorbers].
And here's what makes chromatography so revealing: most petals don't use just one pigment — they use a mixture. The colour you see is a blend, the same way a screen makes any colour from just red, green, and blue light (which you can explore in [What Colour Is Your Shadow]).
The pattern of bands on your strip is like a chemical fingerprint for that petal. Two petals that look identical in colour might produce completely different band patterns — meaning completely different chemistry inside them. And two petals that look totally different might share one or two of the same bands — meaning they have at least one pigment in common.
Curiosity spark: What do you think would happen if you mixed the extracts from two completely different-coloured petals and ran them together on one strip — would you see all the bands from both, or would something unexpected appear?
Find out in The Crazy Scientist Lab.
Teachers & Homeschoolers: Print-ready HD versions of this Science Behind It poster and companion G&T Challenge Card are available inside The Crazy Scientist LAB.
Extension: G&T Years 5 & 6
Teachers & Homeschoolers: Print-ready HD versions of this Science Behind It poster and companion G&T Challenge Card are available inside The Crazy Scientist LAB.
Vocabulary
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READY TO TEACH THIS
TOMORROW?
Running the experiment is easy; however, teaching it well is another challenge.
Teachers often ask:
How do I adapt this for Stages 1,2 or 3?
What do I do with fast finishers?
What misconceptions will they have?
How do I structure this for a full class?
What syllabus outcomes does it cover?
What do I say when they ask WHY?
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