Kendra is doing an experiment to see which brands of popcorn leave the fewest unpopped kernels. she popped one bag at a time for four minutes each. she tested four brands: jiffy pop, pop secret, great value, and redenbacher’s. at the end of the four minutes, she opened the bag and counted the number of unpopped kernels, recording the data. she repeated her experiment four times and recorded the average number of unpopped kernels in her data table. 7. independent variable 8. controlled variable 9. responding variable a. the number of unpopped popcorn kernrls b. the brand of popcorn c. the time the popcorn is cooked