observation is made using one or more of the five senses. An independent variable is a variable that’s changed in an experiment. An explanation based on an observation is a/an . There may be only one variable in an experiment. observation is made using tools or measurement. What’s the difference between an observation and inference? Read the experiment. Then, match the term on the left with its definition on the right. 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. Term Definition 7. Independent variable a. The number of unpopped popcorn kernels 8. Controlled variable b. The brand of popcorn 9. Responding variable c. The time the popcorn is cooked