Materials:

Thin cardboard from a cereal box- a bar of soap – pencil - scissors – bowl filled with water.

• Instructions:
• 1.  Cut out each of the boat drawings on this page and use a pencil to draw some boats on the side of the cereal box that doesn’t have any words or drawings. 
• 2.  Use the scissors to cut out the boat pictures you just drew. 
• 3.  Break off a small piece of soap the size of a pea.  Put it in the hole in the back part of one of the boats. 
  
  4. Make the boat float on the water, with the side with the drawings facing up.  What happens?  (Empty out the bowl and fill it with water again before trying a second boat.) 

Ask yourself:

Why do the boats move?

Can you make boats from other materials?

Are the boats really moving?

Explanation:

Normally, the molecules on top of the water get so close to each other that they are almost squashed together.  This creates something called surface tension.  In this case, the soap loosens the bonds between the water molecules and stops them from getting so close together.   When you put the boat in the water, the water molecules in front of the boat separate with more force than the molecules near the soap at the back of the boat.  This makes the boat move forward and continue moving until the soap has covered the entire surface of the water.  It’s because of this that you need to change the water every once and while.  Put a piece of soap on the corner of the boat instead of the hole in the back.  What happens?