Why do humans grow only two sets of teeth?
O que torna o ser humano único? (What makes human beings unique?)
How do we hear?
What is the function of flies and mice within their ecosystems?
Para que existen las moscas y los ratones? (Big Question originally submitted in Spanish).
Why are tears salty?
Why can it be important to grow your own garden produce?
What is the process of evolution?
Why is blood red?
¿Porque la sangre es de color rojo?
Why can you find ants in most countries on earth?
Which was the first organism on earth?