Lead students to the notion that amount of absorbency could also be a consideration. Divide the class into three groups. Each group will test one of the three prototypes. Have partners test the absorbency of a prototype by dropping 15 ml of water from a dropper onto the center of a sheet of paper towel. Students place a transparent grid over the top of the paper towel and use a transparency pen to trace around the stain on the paper towel.
Students then count the squares covered by the stain to determine the surface area.
Record data from the experiment on a large class chart. Students then compare the results of the absorbency test to determine which paper towel is the most absorbent. Discuss the idea that the prototype with the least surface area would be the most absorbent. Have students discuss which paper towel they would purchase and the reasons for choosing that particular prototype.