Objective Students make predictions then control variables as they test to see which pen works best without the help of gravity. Through reading and experimenting, students gain new understandings about gravity's effects and technological design.
Ink flows slowly down the barrel to a tiny ball in the tip.
As the ball rolls, it transfers ink onto the paper. When inverted, ballpoints will deposit the ink that's clinging near the tip. But soon, the ink responds to gravity's pull - it flows back down the barrel and the pen no longer writes. Factors such as the stickiness of the ink, the amount of ink in the barrel, the width of the barrel and the width of the ballpoint affect writing time. Roller balls and felt-tip pens rely less on gravity.