Making Glass
How is glass made? (Heat sand, soda ash, and lime until liquid, cool into non-crystalline solid.)
Why Is It?
Cicada Cycles
Why are cicada cycles always prime numbers? (Prevents specialist predators from developing)
Cicada Emergence
How do cicadas know when to emerge? (Don't know -- might be sensing something in tree sap)
Bug-Eating Plants
Why do some plants eat bugs? (They live in nutrient-poor habitats; bugs have lots of nutrients.)
Twinkling Stars
Why do stars twinkle? (Atmospheric turbulence bends the light, and our pupils are small.)
Baby Armadillos
Do armadillos always have identical quadruplets? (Yes, indeed, but no one knows why.)