1+1 is not always 2

Aim of the science project:

The aim of this science fair project is to demonstrate that 1+1 does not need to be always 2.
Materials Required:
  1. a clear glass quart jar
  2. 1 cup of sugar
  3. a measuring cup
  4. masking tape
  5. a pencil or a pen
Procedure
  1. Take the jar.
  2. Take a  strip of masking tape and place it down the outside of the jar.
  3. Then fill the jar with 1 cup of water.
  4. The water level on the tape should be marked.
  5. Now add one more cup of water into the jar and mark the water level on the tape again.
  6. Make the measuring jar empty and dry it.
  7. Next step is to fill the jar with 1 cup of sugar.Make sure that the 1 cup mark on the tape is at the top of the sugar.
  8. Pour  one cup of water into it.
  9. Stir it well and keep the measuring jar for other experiments.
Results:
It is seen that the  liquid level  is below the 2 cup mark.
Why is it so?
The explanation behind this is that there are spaces between the sugar grains and the water moves moves into these spaces.As a result the volume becomes less than 2 cups.We know that water and sugar are examples of matter and cannot occupy the same space at the same time.Moreover,the cup of sugar is not completely solid. That is why the volume decreases.