Why Does Your Crazy Bean Move Like That?

There’s no motor hiding inside your Crazy Bean — just a marble, gravity and forces.

When you give the bean a gentle push, the marble inside begins to move. As the bean tips, gravity pulls the marble towards the lower end.

Then — BUMP!

The marble reaches the end of the bean and pushes against the foil. This shifts where the bean’s weight is and can make the whole bean tip, flip or change direction.

Why Does It Keep Flipping?

As the bean flips onto its other end, the marble rolls again.

The weight shifts.

The bean tips.

The marble moves again.

That repeating movement is what gives your Crazy Bean its strange, almost lifelike motion.

What Did Marble Size Change?

In your investigation, you changed the size of the marble while trying to keep the rest of the bean the same.

Different-sized marbles can also have different masses. A marble with more mass can produce a different effect when it rolls and bumps into the end of the bean.

But your results are the important part.

What did YOUR evidence show?

Did one marble make the bean:

• flip more often?

• travel further?

• change direction more?

• move faster or slower?

Scientists don't just say what they think should happen — they use observations and evidence to explain what actually happened.

The Big Science Idea

Your Crazy Bean moves because forces change motion.

Gravity moves the marble inside.
The marble pushes against the bean.
The surface pushes back on the bean.
Friction affects how it moves across the surface.

And because the marble is constantly moving inside, the forces acting on the bean keep changing.

That tiny marble turns a simple foil tube into a surprisingly complicated moving system!