Oct 27: Surface Tension Experiment

Issue 198

Mar - Apr 2026

Black-Backed Gulls
Meth & HIV in Fiji
Dung beetles
Centro
Rogaining

Subscribe

Talking points

Gull spotting

• Editorial

For shame

• In the field

When black-backs attack

• In the field

Two years on Mana Island

• Geo News

Before the flood

• Geo News

A delicious crayfish circle of life

Below are some talking points and activities to pass the time, all relating to today’s story.

Talking points

Discuss the ideas presented in the story with your family—at home or over video conferencing. Find ways to involve as many people as possible, especially those who you know are isolated by the lock-down.

• Mayflies look similar to dragonflies and damselflies. (One of the differences between them is the mayfly’s mass-hatching.) What are your experiences seeing dragonflies, damselflies and mayflies? Can you tell them apart?
• Mayflies are described as “the link between algae and fish.” Could you draw a diagram that shows how algae, fish and mayflies are connected?
• Mayflies (and their relatives, the dragonflies and damselflies) offer “a reasonably accurate representation of the health of a particular waterway.” What do you think this means? In the stream or waterway nearest to where you live, are there any mayflies, dragonflies or damselflies, and what does that tell you about the health of that waterway?
• A fossil imprint of Bojophlebia prokopi, the world’s largest mayfly, was found in the Carpathian Mountains and dates back about 300 million years. Its wingspan was 450mm. Measure this out to see how big it was. What might it have been like to see? Do you think those large wings made any noise? Which creatures do you think might have preyed on them?
• When they hatch, mayflies “struggle through the viscous membrane” of the water’s surface. What do the words “viscous” and “membrane” mean? What are the “two worlds” that are separated by the viscous membrane of the water’s surface?

Activity: Surface Tension Experiment

Hatching mayflies must struggle to fly upwards from the water’s surface. Explore the concept of surface tension with this simple paperclip experiment.

You will need:

• A magazine picture
• Medium-weight cardboard
• Scissors or craft knife
• Glue
• Pencil
• Eraser

Step One: Your first challenge is to get one paperclip floating on the water. This is not easy – if you just put a paperclip into the water you’ll find it sinks straightaway. A good technique to get your paperclip floating is to lower it in, balanced on another paperclip which “cradles” the second. To make your cradle paperclip, bend one arm upwards and use this as a handle.

Step Two: Once the paperclip is floating, gently remove the “cradle” paperclip. What is keeping your paperclip afloat? (The water molecules are tightly bunched together forming a dense surface that can support the weight of the paperclip.)

Step Three: Dip the toothpick into dishwashing liquid. Allow a drop of dishwashing liquid to fall onto the water. (It doesn’t need to be near the paperclip for this to work.) What happens? Does the paperclip instantly sink? Why does it do this? (As a surfactant, the dishwashing liquid pulls apart the water molecules so the surface tension is interrupted and stops supporting the paperclip.)

Send us a picture of you and your paperclip floating!