Scientific Method - Online Tutor, Practice Problems & Exam Prep

The scientific method is a systematic approach to inquiry, beginning with observation and question formulation. It involves hypothesis creation, experimentation, data collection, and conclusion drawing. Key concepts include distinguishing between predictions, hypotheses, and theories. A prediction forecasts an outcome, while a hypothesis provides a testable explanation. Theories are broad hypotheses supported by substantial evidence. Fundamental biological theories include cell theory, homeostasis theory, and the theory of evolution, all emphasizing the interconnectedness of life and the importance of empirical evidence in scientific understanding.

Scientific Method

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 textbook has been subjected to the scientific method. So then the question becomes, well, what in the world is this scientific questions, test, 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 textbook 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. 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 work. 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. So in our next video we're going to distinguish between predictions, hypotheses, and theories. So I'll see you guys in that video.

Predictions, Hypotheses, & Theories

In this video, we're going to distinguish between predictions, hypotheses, and theories. A prediction is defined as an expected outcome of an event that can either be correct or incorrect. It addresses the answer to the question, What will happen? For example, I could make a prediction that tomorrow it will rain. Tomorrow, it will either rain or it will not, so my prediction of this expected outcome will either be correct or incorrect.

Now, the hypothesis is a bit different; it is defined as a proposed and testable explanation for an observation. The explanation here is very key. A well-designed hypothesis addresses the answers to two questions: What will happen, and why will it happen? The "why" is where the explanation plays a significant role. Since it answers the same question, "What will happen," as the prediction does, a good hypothesis will also include a prediction. For example, if we go back to the rain example, I could make a hypothesis that tomorrow it will rain because I pointed to the sky. A hypothesis might not always be true, but it will always be testable and include an explanation for both what will happen and why it will happen.

The last term, theory, is defined as a testable and broad hypothesis of many observations supported by a large body of evidence. The theory is, in many ways, similar to the hypothesis. It is distinguished by being broader, involving many observations, and supported by a substantial body of evidence. For example, with the rain scenario, a theory could state that every single time I point to the sky, it will rain the next day, explaining both why and what will happen on a much larger scale.

Below, we have another example applying the three terms prediction, hypothesis, and theory. Here on the left, we're starting the scientific method with an observation and a question. The observation is that the lawnmower won't start. A prediction could be that the lawnmower will start if you add gas. This prediction can either be correct or incorrect. A hypothesis might be that the lawnmower stopped working because it ran out of gas, so if you add gas, it will start working. This hypothesis answers both what will happen and why it will happen. A theory in this context would indicate that all lawnmowers stop working when they run out of gas and will start working when you add gas, applying this explanation to a broader range of observations.

It is essential to note that technically, hypotheses and theories can never be proven correct but can always be falsified, meaning they can be proven incorrect. This is why you must either accept or reject a hypothesis or a theory without claiming it to be true or correct. There are many theories in biology, and while they can be supported by many observations and substantial evidence, they can always be falsified or proven incorrect in the future. This concludes our lesson on distinguishing these three terms, predictions, hypotheses, and theories. Moving forward, we'll get a bit of practice, so I'll see you guys in our next video.

Scientific Method Example 1

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 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.

Which of the following shows the best order of steps of the scientific method?

• A. Observation → Data Analysis → Hypothesis → Conclusion → Peer Review & Publish → Experiment.
• B. Observation → Hypothesis → Experiment → Peer Review & Publish → Analysis → Conclusion.
• C. Observation → Hypothesis → Experiment → Data Analysis → Conclusion → Peer Review & Publish.
• D. Experiment → Hypothesis → Observation → Data Analysis → Conclusion → Peer Review & Publish.

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.

Alright. So here we have a practice problem that says, a scientist observes that even after sterilizing broth, cells reappear in the broth over time. The scientists then ask the question, why do cells reappear in the broth after sterilization? And then designs and conducts an experiment. Considering this, appropriately label each of the following blanks down below right here as either a prediction, a hypothesis, or a theory. And so notice that we've got each of these 3 blanks down below that correspond with the sentence that follows. And so, what we need to recall from our previous lesson videos is that a prediction is an expected outcome of an event, and of course, the prediction is really only going to answer the question what will happen. Now recall that the hypothesis is going to be a testable explanation for an observation. And so not only will it answer the question what will happen, but it will also answer the question why it will happen. And then also recall from our previous lesson videos that the theory is really just a testable and broad hypothesis. And so really the key word here is that it is going to be broad. So keeping this in mind, what we can do is take a look at the first blank here, which says cells will only appear in the broth exposed to a source of preexisting cells. Now this sounds like it's answering the question what will happen. Cells will only appear in this broth when they're exposed to this. But it does not answer the question why it will happen. Why is it that the cells will only appear in this broth when it's exposed to pre-existing cells? Why? And that why is not fully answered. And so that means that this first one is going to be the prediction. Now moving on to the next blank here it says that cells will appear only when pre-existing cells grow and divide. Therefore, cells only appear in exposed bras. So this part over here, cells only appear in exposed bras, is basically answering the question what will happen. However, to say that cells appear only when pre-existing cells grow and divide, that's answering the question of why it will happen. The cells will appear in the exposed broth because cells only appear when pre-existing cells grow and divide. And so because this one is answering the question to both what and why it will happen, This will be the hypothesis. And then, of course, last but not least, what we have is this last blank here, which says all organisms consist of cells and all cells come from pre-existing cells. And so because it's including all organisms, it's very very broad, and that means that this will be the theory. And it turns out that this theory here that all organisms consist of cells and all cells come from pre-existing cells is actually a basic fundamental theory that we will introduce in our next video. And so this here concludes the answers to this practice problem, and I'll see you guys in our next video.

Basic Theories of Biology

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 preexisting 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 theory pretty much says that all living organisms are going to be able to maintain a relatively consistent 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 3rd 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.

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.
• D. All cells arise from preexisting cells.

Here’s what students ask on this topic:

What are the steps of the scientific method?

The scientific method consists of seven steps: (1) Make an observation, (2) Ask a question, (3) Formulate a hypothesis, (4) Design and conduct an experiment, (5) Collect and interpret data, (6) Draw conclusions, and (7) Peer review and publish. This systematic approach ensures that scientific inquiries are conducted in a structured and reliable manner, allowing for the validation and replication of results. Each step builds upon the previous one, starting with an initial observation and culminating in the publication of findings, which are then subject to scrutiny by the scientific community.

What is the difference between a hypothesis and a theory?

A hypothesis is a proposed and testable explanation for an observation, addressing both what will happen and why it will happen. It is specific and can be tested through experimentation. A theory, on the other hand, is a broad hypothesis that has been extensively tested and supported by a large body of evidence. Theories explain a wide range of phenomena and are considered robust scientific explanations, although they remain falsifiable and can be disproven with new evidence.

Why is peer review important in the scientific method?

Peer review is crucial in the scientific method because it ensures the accuracy, validity, and reliability of scientific findings. During peer review, other experts in the field evaluate the research methodology, data analysis, and conclusions to identify any errors or biases. This process helps maintain the integrity of scientific literature, promotes transparency, and fosters trust in scientific results. Peer-reviewed studies are more likely to be credible and are essential for advancing scientific knowledge.

What are the basic theories of biology?

The three basic theories of biology are: (1) Cell Theory, which states that all living organisms are made up of cells and all cells come from preexisting cells; (2) Homeostasis Theory, which posits that all living organisms maintain a relatively consistent internal environment; and (3) Theory of Evolution, which suggests that all living organisms evolved from a single common ancestor. These theories are supported by substantial evidence and provide a foundational understanding of biological processes.

How do predictions differ from hypotheses in the scientific method?

Predictions and hypotheses serve different roles in the scientific method. A prediction is an expected outcome of an event, addressing the question of what will happen. It can be correct or incorrect based on the results of an experiment. A hypothesis, however, is a proposed and testable explanation for an observation, addressing both what will happen and why it will happen. A well-structured hypothesis includes a prediction and provides a rationale for the expected outcome.