I was wondering, is dirt needed for a seed to start to grow?

Yesterday, I was contemplating if it was possible to make a seed sprout without dirt. I figured that it would do me no good just thinking, so I made myself a little experiment. I poured water into a cup so that it was one centimeter deep. Then I put a bean seed into the cup and set it in front of my window.

I waited until today, and when I checked my bean, it was quite bigger. I suspect that the bean absorbed some water, causing it to expand.

I am hoping that by tomorrow the bean will begin to sprout. Remember, if you read this please feel welcome to leave comment.

~Blogdude~