Or you could divide them into groups of two or three. Distribute the student article, activity and data sheet. Have students read the student article. Go over the activity sheet. To make a meaningful scientific test, one of these variables has to be controlled, or kept constant.
Students are now ready to gather their materials and perform the activity.
You may want to discuss the results and conclusions as a class. Or you could collect and assess the data sheets, including answers to the bonus questions. Or, for an open-ended assessment, try the Astro Ketchup extension below. Answers Conclusions depend on the pens tested, though generally felt-tip will be the clear winners because capillary action keeps the ink flowing through a fibrous core. In the experiment, gravity is still present, working against the action of the pen.