Alex

The Disobedient Hoop

Alex has found a hoop that doesn't seem to know which way it's supposed to go!

Throw it forward and it can suddenly stop, change its mind and roll BACK towards you.

No strings. No magnets. No one secretly pulling it.

So what's making the hoop disobey your throw?

Your mission: make the hoop come back — then investigate what controls its strange return journey.

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MEET THE TEAM

Ages

7-12 yrs

Duration

min

10

Difficulty

Easy

Stage

Stage 2-3

Cite this resource

All Categories

Created by Darin Carr (BSc, DipEd)
NESA Accredited Teacher · Chemistry & Physics Specialist · 30+ years in-class teaching
Resource Version: 1.0
First Published:

Last Updated:

7 May 2026

15 Aug 2026

Experiments >

Forces, Motion & Balance

>

The Disobedient Hoop

MISSION VERIFIED

Classroom tested. Teacher designed. Safe at home.

Practising NESA accredited

Australian Science Teacher

★ 30+ years of classroom experience

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Before you investigate... watch the mystery

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Mission Equipment

Gather your materials and get

ready for an amazing mission!

·A smooth, flat floor — tiles or floorboards work best
Open space of at least 5 metres in front of you
Optional: chalk or tape to mark the starting position and measure return distance

Let’s Investigate

Follow the missions steps below to solve the mystery.

1 Make Your Prediction

Hold the hoop upright.
Imagine throwing it forward while at the same time making it spin backwards.

What do you think will happen after it touches the floor?

PREDICT

OBSERVE

EVIDENCE

ASK

SAFETY

TIP

PREDICT

Gather your materials and get

ready for an amazing mission!

2 Make It Disobey!

Hold the hoop upright and prepare to throw it gently forward.
As you release it, flick your wrist to give the hoop strong backwards spin.
Release it into the clear space and watch carefully.

PREDICT

OBSERVE

EVIDENCE

ASK

SAFETY

TIP

PREDICT

Gather your materials and get

ready for an amazing mission!

3 Change the Spin

Now investigate the mystery.

Try the throw several times, but change how much backwards spin you give the hoop.

Try:

Little backspin → Medium backspin → Lots of backspin

Keep your forward throw as similar as you can each time.

PREDICT

OBSERVE

EVIDENCE

ASK

SAFETY

TIP

PREDICT

Gather your materials and get

ready for an amazing mission!

4 The Disobedient Hoop Challenge

Now see how much control you can get.
Can you make the hoop travel forward and then return as close to you as possible?
Change only one thing at a time as you improve your technique.

PREDICT

OBSERVE

EVIDENCE

ASK

SAFETY

TIP

PREDICT

Gather your materials and get

ready for an amazing mission!

1 Big Title

Every experiment follows The Crazy Scientist Lab Learning System™ — a simple way to help kids think like real scientists.

LINK to what they already know,
ACTIVATE curiosity through hands-on discovery
BUILD understanding that actually sticks.

Skid a ball across a floor — it slows down. Slide a book across a table — it stops. Friction slows things. That is what friction does. That is ALL friction does.

Right?

What if friction could do the opposite — take something moving forward and send it rolling the other way?

Predict: can friction reverse a direction of travel? And if it can — what would that look like?

Write it down. Then watch.

You just watched a hoop travel forward — then reverse direction — with nothing visibly pushing it back.

Think back to the exact moment it changed direction. Describe what you saw: fast or slow? Did it stop first, or turn smoothly?
What was the only thing different between the first throw and the second?

Nothing hit the hoop to reverse it. Something at the contact point with the floor did. What was happening there — and in which direction was that force acting?

The hoop slowed before it reversed. If friction only slowed it, it would have stopped. Something else pushed it backward. Where did that backward push come from?

Friction usually slows things down. Here, friction reversed an entire direction of travel.

The spin and the throw were fighting each other at the contact point — and friction decided the winner.

If you ran this experiment on ice instead of a wooden floor, would the hoop still come back? What would happen — and why?

"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 stop after their first discovery.

They ask new questions, collect more evidence and test their ideas in different ways.

Where could you take this investigation next?

Does a bigger hoop return from further away than a smaller hoop?

What happens to the return distance if you spin the hoop faster but throw it with the same force?

Dr Puddledrip’s Science Tip

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Read the Science

Why does the hoop come back?

When you release the hoop, two motions are happening at once: the hoop is travelling forwards, but it is also spinning backwards.
When the hoop touches the floor, the bottom of the hoop slips against the surface. Friction acts at this contact point.
This friction slows the hoop’s forward movement while the backspin continues to affect how the hoop moves.
Eventually, the forward movement stops. If there is still enough backspin, the hoop grips the floor and begins rolling backwards towards you!

The secret is the combination of BACKSPIN + FRICTION.

Why is friction the hero rather than the villain?

We often think of friction as the force that slows things down. But friction can do much more than that.

In this experiment, friction between the hoop and the floor helps change the hoop’s motion.
Without enough friction, the hoop would simply slip across the surface and its backspin wouldn't grip the floor properly.
Once the hoop gets enough grip, its backwards rotation can make the whole hoop begin rolling backwards.

So friction isn't just stopping the hoop...

It's helping the hoop change direction!

Would a rougher floor always make the hoop return better? That's something you could investigate.

Why does a gentle throw with lots of spin work best?

There are two things you are controlling when you launch your hoop:

How fast it travels forwards and how fast it spins backwards.

Throw it forward too strongly and the hoop has lots of forward motion to overcome.
Give it too little backspin and there may not be enough backwards rotation left to produce a dramatic return.
A gentle forward throw with strong backspin gives the hoop a much better chance of slowing, stopping and rolling back.

That's why getting the launch just right can take a few attempts.

You're balancing forward motion against backwards spin.

Real-world connection

Ever watched a tennis player make a ball behave strangely after it bounces?

Tennis players deliberately use topspin and backspin to change how the ball interacts with the court.

When the spinning ball hits the surface, friction between the ball and the court affects its motion. Different amounts and directions of spin can change the ball's bounce, speed and direction.

Your disobedient hoop is showing another example of how spin + friction can produce surprising motion.

Try next

• See another experiment where friction is the key to what happens — or doesn't → [The Ghost Glider]

• See Newton's First Law working on a spinning object in orbit → [The Runaway Planet]

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.

Scientist's Challenge

Designed for HPGE, gifted learners and children who enjoy an extra challenge.

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.

The Next Question...

You've solved today's mystery. Now discover where curiosity can take you next.

Why does the hoop store energy in its spin?

When you throw the hoop with backspin, you’re giving it two kinds of energy at once:

forward motion (translation)
spin (rotation)

Friction at the floor doesn’t just slow the hoop — it moves energy from one form to the other. As the hoop slides, friction drains the forward motion but strengthens the spin. The return journey is simply the spin “paying back” the energy friction stored earlier.

Question: If you doubled the spin but kept the throw the same, how would the return distance change?

Why can friction reverse motion instead of stopping it?

Friction always acts at the contact point. With backspin, that contact point is trying to move backward relative to the floor. The floor pushes forward on that point — and that forward push is what eventually rolls the hoop back. Friction isn’t the villain here. It’s the steering wheel.