Subject
Life Science
Objectives
In this lesson the students will understand the factors that impact buoyancy through a little friendly competition.
Materials
- Container to fill with water (plastic tub, sink, etc.)
- Tin foil, cut in to squares (one for each student)
- As many pennies as you can find!
- Buoyancy Slideshow
Background
Buoyancy means the ability to float. There are multiple factors in understanding an objects ability to float. The first factor to understand is water displacement. Water displacement is the amount of water that was displaced when an object was added to the body of water, the water level will rise because space is now occupied by the object. To understand this, think about a bathtub, when you get into a bathtub, filled to the brim with water, it will overflow. The water that is now on the floor has been displaced, the weight of the water and the weight of the object will determine its buoyancy.
The next factor in understanding buoyancy is density. Say you have a bowling ball and a beach ball that are the same size (therefore the same volume) you might think they displace the same amount of water, but they do not. The bowling ball and the beach ball have different weights, one will sink and one will float, and because of this they will displace a different amount of water. The beach ball will displace only its weight in water.
The last factor to understand is surface area. The idea with this is that if something’s weight is distributed over more area it may make it more buoyant.
Procedure
- Present the Buoyancy Slideshow and explain the boat building experiment.
- Fill your container with water
- Hand out a square piece of tinfoil to each student, all pieces of the tinfoil should be the same.
- Once the students have made their boats they will test if they float and begin to add one penny at a time until it sinks. Whoever’s boat held the most pennies wins.