1. Which freezes first? Hot water or cold water? Fill two same sized glasses with the same amount of water and place outside at exactly the same time. Common sense might tell you that the cold water freezes first since it is already closer to the freezing point of water. But is common sense correct? What happens when you reduce the volume of water? Half the water? Quarter full? Etc.? Try out different volumes of water to see if it has any effect on which temperature of water freezes first.
2. Place a full, non-opened can of pop outside and wait for it to freeze. What happens? Try different types of pop. Does one can freeze more quickly than another? Setup a video camera to see the freezing in action. It may take awhile, so make sure your camera has plenty of memory.
We'll be trying out a few things at my house and I'll post results here when they come in. The pop can freezing requires a video camera, because inevitably the freezing action happens when you're not looking!