Super Soapy Boat

This is a fun and simple science activity that will further your exploration of surface tension. With an index card, you make a boat that will zoom across the water, and all you will have to do is squeeze a drop or two of liquid dish soap.

Check Super Soapy Boat out in action!

Super Soapy Boat Supplies

What you will need:

Index card (3×5 inch index card or piece of a manila file)

Pencil

Scissors

Sink (or large container)

Water

Liquid Dish Detergent

Journal

Result timing:

1 minute

Instructions for The Super Soapy Boat

What to do:

First, draw an outline of a rowboat on the index card (pointed at one narrow end, squared off at the other end).
Next, cut out your boat, adding a small square notch in the center of the squared end.
Then, fill the sink or large container halfway (make sure the sink or container is clean beforehand with no soap or dirt left in it if you have to redo the experiment like we did make sure you clean and put fresh water when you try again).
Next, place the boat gently on top of the water at one end of the sink.
Then, squeeze a drop or two of the dish detergent into the space where you cut the notch out of the end of the boat.
Make sure you write down what happens in your journal and draw a picture.

How The Super Soapy Boat Works

At first, the boat sits on top of the water without moving. The tiny molecules that make up the water stick together very tightly, so they form a kind of “invisible skin” on the top of the water which holds the boat in place. This “invisible skin” is called surface tension. When you add the dish detergent, the detergent breaks up the surface tension and the boat zooms ahead.