HEL The students conducted a class investigation in which they rubbed a balloon for 30 seconds with different types of material and then placed the balloon on top of paper confetti. They then counted the number of pieces of confetti that were attracted by the balloon. After completing three tests for each type of material, the students calculated the average number of confetti pieces that the balloon attracted for each type of material. Which of the investigation steps provides evidence that fields exist between objects that exert forces on each other, even though the objects are not in contact?