Scientific Method - Video Tutorials & Practice Problems
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Scientific Method
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In this video, we're going to introduce the scientific method. And so here's a question that maybe some of you guys have never thought of before. And it's asking, how can you possibly trust the information that you learned from your science textbook? Well, the answer to that question is you can trust the information in your science textbook because the information in your text book has been subjected to the scientific method. So then the question becomes, well, what in the world is this scientific scientific method is defined as a procedure that is used by scientists to answer questions, test ideas, and gain scientific knowledge. And so this scientific knowledge that has been subjected to the scientific method is going to make its way into your text book so that you can learn from it and you can trust it. And so the scientific method is a series of steps that we'll talk about down below in our image, but the scientific method always starts with an observation and a question. And so if we take a look at our image down below, once again what we have are the 7 steps here to the scientific method. And so again the scientific method always starts with an observation and a question And so the very first step is going to make is going to be to make an observation and the second step will be to ask a question. Now we're going to apply the scientific method to an example that might be a little bit more relatable for you all. And so let's imagine that one night, some evening, you're studying for your biology test, but then you realize that the desk lamp does not work. And so here, notice that we have your desk and we've got the lamp here on your desk, and you're observing that the desk lamp does not work. So that would be your observation. After you've made your observation, you would move on to the second step of the scientific method, which would be to ask a question. And so for example, your question might be, why doesn't the lamp work? After the second step, you would move on to the third step of the scientific method, which would be to formulate a hypothesis and to make a prediction as to, why your lamp might not be working. And in our next lesson video we're going to distinguish between hypothesis and prediction. But for now for simplicity's sake let's just say that the hypothesis is an explanation for your question. And so why doesn't the lamp work? You might think that it's not working because the bulb in the lamp is just simply loose. And really all you need to do is just, screw in that light bulb just a little bit tighter and maybe it'll start working. So after you formulated your hypothesis and made your prediction, you would move on to the 4th step of the scientific method, which is to design and conduct an experiment. And the experiment in your example here might be to just screw in the light bulb a little bit tighter. You just go in and you screw that light bulb tighter. After the 4th step, you would move on to the 5th step of the scientific method, which is to collect and interpret the data from your experiment. And so this would be like checking to see if your lamp actually works after you've screwed in the light bulb a little bit tighter. After the 5th step, you would move on to the 6th step of the scientific method, which is to draw conclusions. And when you're drawing conclusions, you're basically asking, should we accept or reject the original hypothesis that you made over here? So let's say that you screwed in your light bulb a little bit tighter, you check to see if it worked and then all of a sudden it did work. At that point you would accept your hypothesis and move on to the last step here of the scientific method, which is step number 7, which is peer review and publish. By peer review, what this means is that you would get one of your peers, maybe your parents or one of your classmates to check your entire scientific method process. And they would check it for errors and mistakes and things like that. Now if your peers review your process and they approve of it then you can go on to publishing your data, your results, and your conclusions, and you could go ahead and publish primary literature. And really, all of the information in your textbook comes directly from published primary literature that has undergone this scientific method multiple times. Now let's say, for example, that you went through this process here. You screwed in your light bulb a little bit tighter. You checked to see if your lamp worked, but then you realized that it did not actually actually worked. In that case, you would need to reject your original hypothesis. And if you reject the original hypothesis, you would not go to step 7, instead you would go on to, repeat the entire process so it would be a cycle. So then you would have to make an observation, maybe it's the same observation. You would ask a question, maybe it's the same question. But then you would need to formulate a new hypothesis and make a new prediction, and that would require the design and conduction of a new experiment. And, of course, you would repeat this entire process over and over and over until you're capable of accepting your original hypothesis and, publishing your information. And so this here is really the scientific method here and that concludes our introduction to the scientific method. Method. So in our next video we're going to distinguish between predictions, hypotheses and theories. So I'll see you guys in that video.
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Predictions, Hypotheses, & Theories
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In this video we're going to differentiate between predictions, hypotheses, and theories. And so a prediction is pretty straightforward for the most part and a prediction can be defined as an expected outcome of an event that can either be correct or incorrect and so predictions will only address the answer to the question what will happen. And so for example I could make a prediction that tomorrow it will rain. Now tomorrow it will either rain or it will not rain and so my prediction will either be correct or incorrect. And so once again predictions are pretty straight forward. Now a hypothesis on the other hand is often confused with a prediction. However, a hypothesis is different than a prediction and so we can define a hypothesis as a proposed and testable explanation for an observation, and the term explanation is incredibly key when it comes to a hypothesis. And so, a hypothesis will address the answers to 2 questions. It will address the answer to the question, what will happen? And it will also address the answer to the question why it will happen. And so the why here is what ties in the explanation term with this hypothesis. Now because the hypothesis should answer the question what will happen just like a prediction answers the question what will happen, a good hypothesis or a well structured hypothesis will often include a prediction, and so this is why hypotheses are often confused with predictions. However, again, the hypothesis is going to be different because it is going to be testable and it will provide an explanation for the observation meaning it will answer the question why something will happen. And so for example, if we go back to that rain, analogy, I could make a hypothesis that tomorrow it will rain because I pointed to the sky. Now that might sound a little ridiculous, and it's not necessary for you to accept the hypothesis. However, the hypothesis must always be testable, meaning that you can design an experiment to determine if you want to accept or reject the hypothesis. And the hypothesis must always provide an explanation and should answer the questions what will happen and why it will happen. Now, last but not least we are going to discuss theories. And so a theory can really be defined as a testable and broad hypothesis of many observations supported by a large body of evidence. And so really a theory is a broad hypothesis and so in many ways the theory is going to be similar to the hypothesis. But again the theory is going to be much broader on a larger scale and so the key terms that differentiate the hypothesis from the theory are the terms broad, the word many and the word large. Again, the theory is going to be much broader with many observations and large body of evidence. So it's at a it's basically a hypothesis at a much larger scale. And so if we take a look at our image down below we can get a better understanding and look at another example to help us better differentiate predictions, hypotheses, and theories. And so if we take a look here at this image notice that we are starting with an observation and notice we have a motorcycle here and this motorcycle actually won't start and that is our observation. And so after we make our observation that the motorcycle will not start we ask ourselves a question and the question is why doesn't the motorcycle start? Now, if we want to differentiate predictions from hypotheses, from theories that is what these next three boxes are going to be about and so a prediction once again is going to be an expected outcome of an event that can either be correct or incorrect and it will only answer the question what will happen. And so, the prediction here could be, if you add gas then the motorcycle will start. So the motorcycle will start if you add gas, that is simply a prediction because it is an expected outcome of an event but it will either be correct or incorrect. We could add gas to this motorcycle and it will either start or it will not start and so that is a prediction answering the question what will happen if we add gas, but it doesn't answer any other questions. Now moving on, a hypothesis on the other hand is again going to be a proposed and testable explanation for the observation. So it will not only answer the question what will happen but it will answer the question why it will happen as well. And so for example, we could say that the motorcycle stopped working because it ran out of gas. So if you add gas then it will work again. And so notice that it includes the word because here and that because automatically shows that this is an explanation explaining why something will happen. And so it's saying that it ran out of gas that is the explanation and it also answers the question, what will happen? So it says that if you add gas, it will work again. And so this here is going to be the hypothesis. And so you'll notice here in the image that, it's not only, addressing the question, what will happen if we add gas but it's explaining why and it's, the why part is because it ran out of gas and so notice here we have a gas meter that is on empty to show that this is explaining, why this will happen. Now, last but not least over here what we have is, the theory. And so again the theory is very similar to the hypothesis but it's going to be at a much broader scale supported by many observations and it's gonna also be supported by a large body of evidence. And so here with this theory notice that we have multiple motorcycles here so it's not just one motorcycle it's multiple motorcycles and we're looking at a much larger scale here. And so with this theory what we're saying here is that all motorcycles stop working when they run out of gas so adding gas will allow them to work again. And so notice that some of the keywords here are all motorcycles so now it's at a much broader scale than just the one motorcycle we were looking at before. And, it is saying, it is also a similar to a hypothesis in that it's answering the questions what will happen and why it will happen. So it's saying that when they they stop working when they run out of gas that's an explanation and if we add gas they will work again that's answering what will happen. And so the theory is just going to be very similar to the hypothesis but at a much broader, larger scale. And so hopefully this was helpful to help you differentiate between a prediction, a hypothesis and a theory. Now, another important note that I want to mention here is that technically, hypotheses and theories can never be proven to be correct, but they can be falsified meaning that they can be proven incorrect. And so, this is something that's important to keep in mind because, whereas a prediction can be determined to be correct or incorrect, hypotheses and theories can never be proven to be correct and so this is why we can only accept a hypothesis and we can only accept a theory, but we can never say that they are true. And this is an idea that's important to keep in mind because as we move forward in our course we will discuss some theories such as the cell theory and the theory of evolution and again there are large bodies of evidence that support these theories and there are many observations that support these theories, but they can never be proven to be true. They can only be accepted and, they can also always be falsified. So there can always be some finding in the future that may falsify these hypotheses and theories. And so that's just an interesting fact to keep in mind. But again, this here concludes our brief lesson differentiating predictions, hypotheses, and theories and I'll see you all in our next video.
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example
Scientific Method Example 1
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Alright. So here we have an example problem that says, a scientist observed a new phenomenon and wonders how it happens. What is the next step in their study? And we've got these 5 potential answer options down below. And so what we need to realize is that when the scientist observes the new phenomenon and then wonders how it happens, this is really telling us that the first two steps of the scientific method have been completed. And so the observation step and the question step, have both been completed already. And so really what we're looking for here in this, problem is, the next step which would be the third step of the scientific method. And so that would be to essential essentially hypothesize. And so option e here is going to be the correct answer for the next step. Observe has already happened. Experiment does not take place until after the hypothesis has been generated, so that won't be the next one. Design the experiment. Once again, that is not going to happen until after the hypothesis has been created. And then peer review is one of the last steps of the process. And so once again, option e, hypothesize is the correct answer here. And that concludes this example, so I'll see you guys in our next video.
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Problem
Problem
Which of the following shows the best order of steps of the scientific method?
A scientist observes that even after sterilizing a broth, cells reappear in the broth over time. The scientist then asks: 'Why do cells reappear in the broth after sterilization?' and designs/conducts an experiment. Considering this, appropriately label each of the following blanks as either a 'prediction, hypothesis or theory.'
________________: Cells will only appear in the broth exposed to a source of preexisting cells.
________________: Cells appear only when preexisting cells grow & divide; therefore, cells only appear in exposed broths.
________________: All organisms consist of cells & all cells come from preexisting cells.
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3m
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6
concept
Basic Theories of Biology
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So now that we've introduced the term theory in our previous lesson videos, here in this video we're going to talk about some basic theories of biology. And so really there are 3 basic theories of biology that your professors tend to want you all to know. And so notice down below in this table, we're going to show you each of these three theories and the concept that they apply to. And so the very first basic theory of biology that you should know is the cell theory. And the cell theory is pretty much saying that all living organisms are made up of cells and all cells come from pre existing existing cells. And so here we have a little image of a cell. Now once again recall that theories are really just broad hypotheses. And so, we can tell that it's broad here because it includes this word all. Now the second theory that you should be familiar with is the homeostasis theory. And the homeostasis internal environment. And so here what we're showing you is a little picture of a person sweating in the hot sun since sweating is a mechanism that helps to maintain homeostasis. But really all living organisms have this ability to maintain relatively consistent internal environments. And once again, we can tell that this is broad because it includes the word all again. Now the third and final basic theory of biology that you should be familiar with is the theory of evolution. Now the theory of evolution does not say that evolution itself is a theory. Instead, the theory of evolution says that all living organisms evolved from a single common ancestor. And so here what we have is a little image that's used commonly to represent evolution. But the idea here is that, once again, theories can never be proven to be true. Instead, there's a large body of evidence that supports the theory. But once again, the theories will always remain falsifiable, which means that they can be proven to be false moving forward in the future, but once again, they will never be proven to be true. And so there is quite a lot of evidence that suggests and supports all three of these theories. But for now, this here concludes the basic theories of biology that you should be familiar with, and I'll see you guys in our next video.
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Problem
Problem
Which of the following statements about the cell theory is false?
A
All living organisms are made of cells.
B
All cells arise spontaneously.
C
Cells are the basic structural & functional unit of life.