Potato Chip Science: How Greasy Are Your Potato Chips? (page 2)
Your results should roughly reflect the amount of fat listed in the nutrition facts for each brand of chips.
Here’s another way to think about how averages work: since we grabbed a big handful of chips without looking, we got some chips that were big, some that were small, and some that were medium in size. Because we have a lot of differently-sized chips to average together, we can say that any given chip is “about this big.” If we only had two chips it would be hard to pick which one is the closest to the “normal” size, but if we had a lot of them it would be pretty easy to find one good, average size that describes them all pretty well. This is a simple example of the Law of Large Numbers: the more things we test (and the more times we test them), the more accurate our calculated average will be.
Scientists use averages all the time, because the world often doesn’t behave consistently enough to give us exactly the same number every time we do an experiment. Gas mileage, nutrition facts, school grades, and even things like radiation flux for spaceships are all based off of averages. Averages are a way to find numbers that are “characteristic” of a situation or sample, meaning that these numbers closely describe that situation, even if we can’t always predict the exact number we will get each time we perform an experiment!
So what other factors might have influenced our results? We made sure to pulverize each chip so that it released most of its grease, but if your results didn’t match up with what was on the bag, it may be because certain chips release grease better than others when crushed. If you want, you can repeat this experiment and crush each chip even more. See if your results change, and take note of this in your write-up for your project.
There are countless ways to expand this experiment. What if we tried to figure out how greasy a given brand of chips was by weight, as opposed to serving size? This is a useful thing to measure, because some serving sizes might be bigger or smaller than others. We could calculate this measurement by dividing the amount of squares we counted by the number of grams that make up a serving size. We could even get a more accurate measure of greasiness by using a food scale to measure out grams, rather than counting the FDA’s estimated amount of chips that make up a serving size. Remember, the FDA calculated this number by taking an average! This experiment could even be expanded to test how accurate the FDA’s approximate serving sizes are. Can you design an experiment to investigate this using a food scale?
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