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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
One metal slinky or long metal spring — a longer spring (1.5–2 m extended) gives clearer results, especially for longitudinal waves
Two people
A smooth floor with at least 3–4 metres of clear space — tiles or floorboards work better than carpet
How to do it
1
Set spring & tie string
Two students each hold one end of the metal spring.
Walk slowly apart until the spring is stretched out to about 3–4 metres on a smooth floor.
Tie the piece of coloured string around a coil roughly in the middle of the spring
3
Make a Transverse Wave
The person at one end shakes their end of the spring once — a single, sharp flick up and then back to level. The other person holds their end completely still.
Do this several times with single flicks, then try a continuous rhythmic shake to build a steady wave pattern.
5
Make a Longitudinal Wave
Now switch techniques entirely.
Instead of shaking up and down, the student at one end gathers a small bunch of coils toward them, compressing the spring slightly, then pushes them forward toward their partner in one quick motion.
Look for the pulse of compressed coils moving along the spring
2
Make a p[rediction
Predict — after a wave travels from one end to the other, where will the coloured coil end up?
And predict: is there more than one way to make a wave travel along this spring?
Write both predictions down before anything moves.
4
Explore a little
Try varying two things: first, change how fast you shake (faster vs slower).
Second, change how far you shake (bigger vs smaller movements)
Did it work? Share the science! Tag @the_crazy_scientist on Instagram — we love seeing your experiments!
The Wave Factory
Designed by Darin Carr (BSc, DipEd)
NESA Accredited Teacher Chemistry & Physics Specialist
Creator of the LAB™ Learning System
Every earthquake, every sound, every beam of light reaching you right now is a wave. But waves aren't all the same — they travel in fundamentally different ways. With one metal spring and a partner, you can generate both types with your own hands and see exactly how they're different.
5-12 yrs
Easy
15
min
Stage 2, Stage 3
>
The Wave Factory
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.
Think about a wave at the beach. It rolls toward the shore, one after another — the wave is clearly moving forward. But the water itself?
Watch a seagull sitting on the surface. It bobs up and down as each wave passes. It doesn't end up on the beach. The wave moved. The seagull — and the water — stayed.
You're about to make waves with a metal spring.
Before you stretch it out and try anything:
predict — when a wave travels from your hands to your partner's end of the spring, will any part of the spring end up at your partner's end? Or will it stay where it started?
Write your prediction. Then stretch the spring out and find out. And once you've made your first wave — ask yourself whether you can make one that travels differently.
Recall where the coloured marker coil was at the start — and where it ended up after each wave type passed through.
In both the transverse wave and the longitudinal wave, did the coloured coil travel to the other end, or return to where it started?
Think about the direction the coloured coil moved in each wave type. In the transverse wave, which way did it move?
In the longitudinal wave, which way did it move? How were those directions different from each other — and different from the direction the wave itself was travelling?
The wave clearly travelled from one end of the spring to the other both times. But the coloured coil never went anywhere. What was actually travelling — and what was the coloured coil telling you about what the spring was doing?
You've just made both fundamental types of mechanical wave with your own hands. Now think about where each type is working in the world — often invisibly, often at enormous scales.
When a guitar string vibrates, it moves back and forth across its length — at right angles to the string itself.
Based on your wave types, which type of wave is a vibrating guitar string?
And what type of wave does it create in the air around it to reach your ears?
You made a longitudinal wave by pushing and pulling the spring. Sound travels through air the same way — molecules compressing and expanding as the wave passes.
"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 shaking faster change the wave — does a higher frequency (more shakes per second) produce more wave loops along the spring, or does it just make the wave travel faster?
Does shaking bigger change the wave — if you move your hand further up and down (larger amplitude) but at the same speed, does the wave look different?
🧪 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
A wave is energy moving through a medium. The medium — whether it's a spring, water, air, or rock — doesn't travel with the wave. The energy does. Your spring just showed you this twice, in two completely different ways.
The first type you made is called a transverse wave.
When you shook your end up and down, each coil of the spring moved up and then back to where it started — at right angles to the direction the wave was travelling.
The wave shape moved along the spring from your hands to your partner's, but no coil went anywhere. Transverse waves include light, the waves on the surface of water, and seismic S-waves (the side-to-side shaking waves in an earthquake).
The second type is called a longitudinal wave.
When you pushed a bunch of coils toward your partner and pulled back, you created a pulse of compression — coils bunching together — followed by a region of expansion — coils spreading apart. That pulse travelled along the spring as the compression and expansion passed from coil to coil. Again, no coil ended up at your partner's end. The energy travelled.
The spring stayed.
Longitudinal waves are how sound travels. Right now, as you read this, the air molecules around you are being compressed and expanded by the sound waves passing through them — exactly the way the spring coils were. The compression pulse carries the energy from the source to your ears. The air molecules themselves barely move — they just push the next one along, which pushes the next, all the way to your eardrum.
The two wave types are not just different shapes — they behave differently, travel at different speeds through different materials, and carry energy in fundamentally different ways. Understanding both is the foundation of acoustics, seismology, medical imaging, and the physics of light.
Extension: G&T Years 5 & 6
Vocabulary
Know a parent or teacher who'd love this? Send it on! 👇
The Crazy Scientist books
These highly visual books combine storytelling and real science, helping students revisit key concepts and stay engaged long after the session.
Designed by a practising NSW classroom teacher (30+ years experience), these books directly support NSW Science & Technology (2024) outcomes and reinforce “Working Scientifically” skills.
Perfect for classroom libraries or home explorations.
For teachers (YouTube)
— Science Before the Bell
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Quick, curriculum-linked science you can teach tomorro
Try Another Crazy Experiment
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Let's Go!
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Hands-On Science Workshops
Interactive STEM experiences aligned to the NSW syllabus.
