Why didn’t the first paperclip sink?

When you carefully placed the paperclip onto the water, something surprising happened—it stayed on top instead of sinking.

Water molecules attract each other and pull tightly together, creating a very thin layer across the surface. Scientists call this surface tension.

Although this invisible layer is extremely thin, it can support very light objects if they are placed gently enough.

Why could the pond hold so many water bugs?

Each paperclip added a little more weight to the water’s surface.

For a while, the invisible skin stretched and continued supporting the paperclips.

Eventually, the weight became too great and the surface could no longer hold them.

The invisible skin finally broke, causing the paperclips to sink.

Why were everyone’s results different?

You may have noticed that not every pond held the same number of water bugs.

Small differences can affect the results.

For example:

• how gently each paperclip was placed

• tiny ripples in the water

• fingerprints or soap on the paperclips

• the shape and size of the container

Scientists expect investigations to produce different results. That’s why they compare evidence, repeat tests and look for patterns.

Curiosity Spark

Have you ever noticed that adding a tiny drop of dishwashing liquid makes floating paperclips suddenly sink?

Why does soap seem to make the invisible skin disappear?

That’s one of the next investigations scientists explore when studying surface tension.

Discover more in The Crazy Scientist Lab.

Keep Investigating

If you enjoyed this mission, try these next:

• Pepper Escape – What happens when soap touches the surface of water?

• Walking Water – Can water climb uphill?

• Magic Milk Patterns – Watch colours race across the surface when soap changes the water.