Back To CourseEarth Science: Middle School
12 chapters | 101 lessons
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Paul has been teaching middle school science for the last 10 years, and has his bachelors degree in Elementary Education.
Have you ever been reading a book where something was happening, but you couldn't quite figure it out? Possibly a spy novel, or a mystery, or perhaps even a book where you get to pick what the main character does next?
Maybe as you turn the pages in that thrilling 'who-done-it' mystery that you're reading, you start to get a feel for who the real villain might be. As you think back over everything you previously read, you're fairly confident that the butler was the real culprit the entire time; you have evidence that links him to the crime and an overall strong gut feeling about it. It must be the butler! You tell all your friends and make sure that they know that you were the one who said it first!
Books often give clues as to what might happen next. Sometimes you can even make a guess as to what is going to happen by the end of the story. Those guesses might be right, but sometimes they're wrong, too. When you make a guess in a book as to what might happen next, you're probably using clues from what's already happened to make that guess. In the science world, we call a guess like that a hypothesis.
Within the realm of classrooms, science fairs, and especially science experiments, scientists often need to make an educated guess called a hypothesis, which is a statement that says what scientists think will happen when an experiment is tested. When making your own hypotheses, scientists generally follow a few guidelines. The hypothesis is typically a clear statement and, most importantly, needs to be something that can both be tested by experimenting and can be measured.
Let's look at some examples. Pretend you want to perform an experiment with plants where you'd like to see which temperature of water will make plants grow the tallest. One hypothesis could be: room temperature water will make plants grow taller than boiling water. This would be an educated guess because you've only ever seen people water plants with water from a can or faucet, never boiling water, never a boiling pot. Go back to your checklist:
This would be a great example of a good hypothesis because it can be both tested and measured. And don't forget, it's okay if your hypothesis is incorrect. Scientists discover things every day by learning what doesn't work. Let me tell you a story.
Thomas Edison is known for many things, one of which is his work on the light bulb. While he didn't actually invent the light bulb, he did make it better! Originally, light bulbs only lasted a short time, but then Edison and his team started experimenting.
Edison and his team needed to create a new hypothesis every time he tried a new material in his light bulb. Carbonized cotton thread became the material of choice, but Edison wanted his bulbs to last even longer. So, the testing went on: he tried hundreds of things, thousands of things; he tried tree bark; another time, he tried wild grass; one time he tried horse hair, gold, even bamboo - every time he was putting a new item into the bulb he was coming up with a new hypothesis.
Would this type of hypothesis fit our original checklist? Let's see! Can it be tested by experimenting? Yes, as he put each of the items into the bulb and passed a current through them, the materials either gave off light or they didn't. Could those tests then be measured? Yeah, Edison and his team measured by timing how long the materials burned for.
Looking back at our original goal of creating a hypothesis, doesn't a hypothesis need to be correct for it to be valuable? What about being right? Well, Thomas Edison knew that it didn't matter if your hypothesis was correct or incorrect, and so should you. While working tirelessly on the light bulb, Thomas Edison and his team discovered a very long list of things which didn't work very well as light bulb filaments. Edison is even quoted as having said, 'I have not failed. I have found 10,000 ways that won't work.' If your hypothesis proves to be incorrect, don't worry - it happens all the time.
Look over this next list of samples. These are all poor examples of hypotheses as they're written right now. Remember, a good hypothesis will state what will happen when it's tested:
Usually you can spot a bad hypothesis by looking over the check list. Are these all statements? Can they be tested? Can I measure this? Start with the first sentence on the list:
These poor hypotheses are not impossible to fix, however, and they're not even truly bad hypotheses - the idea is there, but they need to be reworded. Take the ice cream example; this could be changed to read: chocolate ice cream melts faster than vanilla ice cream. Now you have a hypothesis that can be tested and measured, and it doesn't rely on the opinions of others.
Remember, your hypothesis needs to be a statement that tells what you think will happen when you test it. By stating that chocolate will melt faster, you could set up an experiment and actually time both flavors. Can you see any way to change the others to something that you could test and that you could measure? What about the question with the milk?
Change that to the statement: whole milk will not turn into butter when shaken in a paint mixer at the hardware store, and then you could test and measure it! You have told everyone what you expect to happen just like when you told about the butler being the prime suspect in your mystery novel earlier. You might be able to test this by going to the hardware store and asking nicely if they would shake up your milk. If it forms butter you were correct, if not, you still know more than when you started.
Scientists often need to make an educated guess called a hypothesis. A hypothesis is what scientists think will happen when an experiment is tested. Remember, when creating a hypothesis there are a few guidelines to keep in mind:
Just like in the novel you were reading, you want to make an educated guess. Think back over what you already know, or do some research before you actually conduct your experiment so that you can make the best guess possible. Don't forget, you learn just as much from an incorrect hypothesis as you do from a correct one, so don't worry if you make the wrong guess. You can always try again!
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Back To CourseEarth Science: Middle School
12 chapters | 101 lessons