CA Raisins  Dancing Raisins CA Raisins  
By Melissa Cruz
Winter 2007

Objective: Observing what is more and less buoyancy. Understanding why certain items float and others do not.

Materials: 
  • club soda that has a lot of bubbles (This won't work if the club soda is flat.)

Activity:
  1. First, pour the club soda in the glass.
  2. Next, drop in half of a raisin.
  3. Wait at least 20 to 30 seconds and watch what happens to the raisin. (The raisin should rise and fall.) 

Reasoning:

The reason why the raisin floats to the top is because the bubbles stick to the sides of the raisin and make the raisin more buoyant. Keep in mind that the bubbles come from the carbon dioxide (from the club soda). If you tried to use tap water, rather then club soda, you will not get the same outcome. Buoyant means that something floats more easily. The carbon dioxide makes some objects float in the same way that a life jacket helps a person float. Together the life jacket and the person are less dense than the water; so the person floats.

Remember that it's the bubbles (the carbon dioxide in the club soda) that makes different objects float.


Other Observations:

1. Can I get something that is heavier than a raisin to float, like a popcorn kernel?

2.  You can try and use a grape. It has a smoother surface then a raisin. Does the surface of the object matter? How about the size?


References:
Sample Video of Experiment (Compliments of You Tube)
PBS Kids Website
Making Science Make Sense)