Wheels and Cranks

What would the world be life if we didnt have wheels? How do you think theancient Egyptians moved huge stones to build the pyramids? Why does a mountainbike hav... » 

What would the world be life if we didnt have wheels? How do you think theancient Egyptians moved huge stones to build the pyramids? Why does a mountainbike have such thick knobby tires? How do you think toys moved before batterieswere invented? This title shows you how different kinds of these two simplemachines are all around you to make your work and play easier. «