Why would someone get different results when conducting the same experiment

You must have a control variable in your experiment, which is something you can change. You should also do your experiment two or three times to see if you get different results. And the reason you would get different results is if something changed, and it would most likely be the control variable. If you don't understand I can give you an example. Like, if your experiment was to see which brand of batteries last the longest in a flashlight. You would have an independent variable which would be the time that the flashlight because it does not depend on anything. Your dependent variable would be the time you turn the flashlights on because that depends on how long they will last. And your control variable with be the batteries you choose. You can choose a double AA brand, an off brand, and a rechargeable brand of batteries. If you do the experiment the first time and charge the rechargeable batteries for 30 minutes, your experiment will be fine. But the second time, if you only charge the battery for 20 minutes, your results will change. It all depends on the control variable really. And I realize that I have been typing for 9 minutes. I hope this helps.

What are the choices?