Mike Parry, age 8, of Spokane, Washington, for his question:

Why does water freeze at 32 degrees?

This question takes us down to the miniature world of molecules. All water molecules are the same size and the same shape. They also all act alike. They cling together in strings of eight or so    and slither around in games somewhat like follow the leader. As the temperature rises higher and higher, they move around faster and faster. As the temperature drops lower and lower, they move slower and slower. They do this, because they must obey certain strict rules.

If the temperature drops one degree, they must slow down exactly so much. At 33 degrees Fahrenheit, they are moving very slowly indeed. When the temperature drops one more degree, they must stop in their tracks. When that happens, the separate molecules must arrange themselves in different patterns. They lock together in a stiff latticework pattern called a crystal. This solid crystal of water molecules is ice. Water molecules have to build it when the temperature gets too cold for them to move around. This happens to be at 32 degrees Fahrenheit.