Writing about Processes

Number these sentences in the correct order.

1		A ballpoint pen is an uncomplicated object.
2		The ball has two purposes. It seals the tube so that the air will not dry out the ink, and it also allows the ink to come out of the pen.
3		This is called the ink reservoir.
4		In this way, gravity forces the ink onto the ball and out of the pen onto the surface.
5		The first is a plastic barrel.
6		At one end of the ink reservoir, there is a small metal ball.
7		To write with the pen, you hold it upright and press it down as you move the ball across a surface.
8		It has three parts.
9		The ball fits tightly into the reservoir but it can still turn.
10		Inside the barrel, there is a thin tube filled with ink.