For science to day we melted primary colored ice cubes in a cup to create a new secondary color. Many were amazed that you could literally see the ice melting. We learned that putting a red and blue ice cube together they will melt and create purple, red and yellow melted to create orange and yellow and blue made green.
"Are my ice cubes going to melt and be the same as hers?"
"Will it be the same color if I try again with more ice?"
"What makes them melt?"
"Why are they getting smaller?"
and my personal favorite,
"What happens if we put all three colors together?"