My daughters often ask to do a science experiment.  So I turn to Pinterest and hunt for something with few (and free!) materials.  The water experiment from Coffee Cups and Crayons fit the bill.  Just fill two glasses with water and drop some food coloring in.  Place a third empty cup between them.  Fold two paper towels lengthwise and put one end in the food coloring and one end in the empty cup.  Watch the water saturate the paper towel and flow into the empty cup.  My kids were amazed at how quickly the water moved up the paper towel.  It is a great way to see how colors mix.  It only takes a few minutes to see the new color, but the longer you wait the deeper the hue.

Materials:

• food coloring
• three clear cups
• water
• two paper towels