The Scale of the Universe
The Scale of the Universe is an interactive learning tool that lets you explore and compare the size of different things - from the very smallest fabric of space-time, all the way up to the largest structures in the universe. Just use the slider below the viewport to scale up and down (or you can spin your mouse wheel if you have one). You can also click on individual items to read about them.
It's kind of interesting that the human egg cell is near the center point of the scale between the smallest and largest of things...visit here to play with this fun learning tool!