Soap Powered Boats***

Soap Powered Boat

Overview:

In this experiment, students will make mini cardboard boats and learn the concept of water surface tension. This experiment will demonstrate how the soap reduces the surface tension around the boat, which causes the water molecules to pull the boat forward.

Time: 

20 min

Lesson Materials:

*You can use the document in the link below to either: tailor the experiment to your needs or to have a printable version of this lesson plan*

Soap Powered Boats Lesson Plan

The plan is editable and printable. Copy the Google Doc in your own drive and make edits or you can just print.

Soap Powered Boats Lesson Video:

Learning Objectives:

  1. Test and see if cardboard boats will float.
  2. Make small boats out of cardboard or cardstock.
  3. Test to see how soap can power a mini boat. 
  4. Describe how water molecules stay together with surface tension.
  5. Observe how the boat moves forward as the soap molecules move back.

Materials Needed:

  • Tray
  • Water
  • Liquid dish soap
  • Cardboard (preferably 3×5 in.)
  • Toothpick
  • Scissors
  • Food coloring (optional)
  • Index card (if cardboard not available)

Experimental Methods:

Part 1: Preparation

  1. Fill a tray with water.
  2. Cut a cardboard into the following shape:

Part 2: Experiment 

  1. First students should ask themselves what will happen when they add the soap in the small opening at the bottom of the cardboard cutout.
  2. Gently place the cardboard cutout on the tray that contains water. 
  3. Grab the toothpick and dip it in dish soap. 
  4. Dip the toothpick that contains dish soap in the small opening in the bottom of the cardboard cut out.
  5. Observe as the cardboard cutout speeds forward in the water. 

Variations:

  • Show the experiment with different water temperature
  • Use a different type of liquid soap to make the “boat” float

Questions to Think About:

  1. What makes the boat go forward?
  2. Why must the cardboard cutout be in that specific shape?
  3. Can any other soap work for this experiment?
  4. Can we use different liquids like milk or vinegar?
  5. Does the temperature of the water matter when conducting this experiment?
  6. Does the amount of soap matter when you dip it in the water?

Chemistry:

Surface tension is the surface that holds up most items above water or any liquid. It is the strongest part of the liquid. The soap breaks that surface tension which pushes the boat forward.

Society:

We can think of this experiment when we wash our dishes. We can think of our boat as oil on our dish. The soap molecules disrupt the arrangement of water and oil on our dishes allowing them to mix and get washed off the plate.

Logistics:

STEAM Subjects: 

Science (Chemistry)

Science Vocabulary: 

Surface tension, water and soap molecules, cohesion

References: