Simple Displacement

• Fill a glass with water to a certain point, taking care to mark it off with a non-permanent marker. Next, put something in the glass with the water. This can be anything you want, really --- a spoon, a rock, a pen or or anything else that has some mass. Observe what happens to the water. It will rise in the glass thanks to the mass displacement from the object you put in with it.
  
  

Pressure Displacement

• Fill a cup with water to a certain point. Next, put a smaller, open container in the glass and push it down, recording what happens to the water as you do so. Compare this to what happens when you push a closed container down. The water will rise in both instances, but not as much in the first instance, as the water can go inside the second container, thus reducing the amount it has to rise.
  
  

Melting Water

• Fill a glass with some ice and mark where it sits. Next, leave it out for awhile or heat it up, and record where it rises to. The water level will rise because liquid water is less dense than ice, meaning it takes up more space in spite of being the same amount of water.
  
  

Other Liquid Density

• Fill a glass with some water and mark off where it is filled to. Put a tube in it, then pour honey, karo syrup and detergent down the tube (in that order). The water level will rise, but it will not mix with the other liquids. This is a good way to show density --- since the other liquids are more dense, they rest under the water, pushing it up but not mixing with it. This is a different kind of displacement than the above kind, and it is important for kids to be familiar with both of them.