Scientific Inquiry Process

The scientific method is the process scientists follow to solve problems. Scientists spend much of their time conducting experiments and carefully recording, analyzing, and evaluating the data from experiments. If the data does not support a hypothesis, scientists must form a new hypothesis and conduct new experiments. When the data supports a hypothesis, scientists share their results with other scientists.

Scientific Experiments

What does it mean to be a scientist?

You may have seen TV or read books about what scientists do. For instance, Neil deGrasse Tyson is a popular American scientist who studies stars and planets—and often appears on television.

Neil deGrasse Tyson

You may also know someone who is a scientist. Maybe you have even done science experiments yourself.

In this stage, you will learn what scientists do and how they conduct experiments.

Scientific Inquiry Process

Even if you do not want to be a scientist for a career, you can still think like a scientist using the scientific inquiry process.

Scientific inquiry is how scientists study the world and make explanations based on what they find out from their studies.

Watch the Scientific Inquiry Process video to explore how it works.

Let's Practice

Asking Scientific Questions (1)

Watch the demonstration with an egg in a bottle below.

In your science journal, write one sentence to explain what happened in the demonstration.

What are three questions you have about what you saw?

What do you think it means for a question to be testable?

Check It Out

In science, some questions are better than others. Scientists are good at coming up with simple questions that can be tested. The answers to these questions help explain how things work and can make life better on Earth.

Scientific questions describe a problem and can be tested using scientific inquiry.

Good scientific questions:

Can be tested by an experiment or measurement (like temperature, time, distance, height, or weight)
Build on what you already know
Are not personal opinions
Lead to other important questions

Background Research (2)

Imagine you have been asking your parents or guardians for a pet for quite a long time, and they agreed to get you a bird. But before getting the bird, they tell you to learn how to care for your bird. The first question you may have is: What do birds eat?

This is not the best scientific question, but you still want to know what birds eat.

Pet Bird

In your science journal, answer the question:

1. How can you find information about what birds eat?

Read and Discover

You can ask people, read books, or search online to find information. These activities are known as background research.

Student Researching Online

Background research is an important step in the scientific inquiry process because it helps researchers learn what is already known and ask better questions. Scientists start by looking at similar experiments done in the past and seeing how other people have answered similar questions. With this background information, they can plan their experiments and activities.

To do background research, you can begin by asking your questions to people who may know the answers. It is also important to find information at the library or online.

Writing a Hypothesis (3)

Once you have asked a testable question and done some background research, the next step in the scientific inquiry process is to write a hypothesis, or your best guess, to answer the question.

Look at the image of three plants. In your science journal, write a hypothesis about why you think the plants are of different heights.

Plants of Different Heights

Check It Out

To investigate, you need a way to measure how things changed. Then you can tell what happened when you changed things compared to what would have happened otherwise. Variables are used in experiments.

· Independent variable: what you are changing or testing in an experiment

· Dependent variable: what you are measuring in an experiment.

Watch the video below, then complete the Let's Practice.

Let's Practice

Most experiments also have controlled variables. Controlled variables are the parts of the experiment that are not changed. For example, to investigate plant growth, you might change the water but keep the dirt and sunshine the same.

Plant Experiment

If you are not sure which variable is which, ask yourself:

"What is being changed?" (independent variable)
"What am I measuring?" (dependent variable)
"What am I not allowing to change?" (controlled variable)

Once you know the independent and dependent variables (and how you will measure them), you can use them to form a hypothesis.

A hypothesis is an "If … then" statement, such as: "If the air becomes more polluted, then more people will get sick." The independent variable is the "if" part (amount of pollution), and the dependent variable is the "then" part (number of people who get sick). Here are some tips to tell if you have a good hypothesis:

It is your best guess for answering a testable question
It is in the form of an "If … then" statement
It says how an independent variable will change a dependent variable
It can be tested with an investigation

Which Hypothesis is Best?

Question	Hypothesis	Best Guess	“If…then" Statement	Independent Variable Changes Dependent Variable	Testable
What effect does using plant food (fertilizer) have on plant growth?	Fertilizer makes plants grow faster.	Yes	No	Yes	Not testable (it is written as a true statement)
Does aspirin have a faster headache-relieving effect than ibuprofen?	Do headaches go away more quickly with aspirin or ibuprofen?	Yes	No	Yes	Not testable (it is written as a question)
Do students who get at least 8 hours of sleep have better test scores than students who don't?	If students get 8 hours of sleep, they have better scores than those who do not.	Yes	Yes	Yes	Testable (it is an "if…then" Statement)

Planning and Conducting Experiments (4)

One day, there is a big rainstorm. You go to a nearby lake and find that many fish have died. You suspect poison got into the lake accidentally or on purpose and killed the fish.

Lake After a Rainstorm

In your science journal, answer the questions:

1. Thinking like a scientist, what experiments could you do to solve the problem?

2. What would be your testable question?

3. What would be your hypothesis?

4. Why would it be a bad idea to add chemicals to the lake to see what happened?

Read and Discover

To test a hypothesis, scientists do experiments. Scientific investigations can answer other questions involving observing or looking at information others have already found.

The main purpose of an experiment is to gather information to show if your hypothesis was right or wrong. This information is in the form of evidence or data.

It is important to think carefully about the steps of your experiment before you begin so that you know it will give data to answer your question.

Imagine that you want to learn about the effect of acid rain on plant growth. You ask a testable question and form a hypothesis:

Testable Question: How does acid affect plant growth?

Hypothesis: If a plant receives more acid, then its roots will not grow as long as the roots of a plant that receives no acid.

When planning an experiment, it is a good idea to write down everything you will do, starting with a title and a testable question. An Experiment Lab Sheet helps you plan and carry out an experiment. After the experiment is done and the lab sheet is filled out, you have a record of what you did, and other people can see the results of your tests.

Student Planning an Experiment

Part of planning is deciding what information you will collect and how you will collect it.

For a good plan, you will need to know:

1. What are your independent, dependent, and controlled variables?

2. What measurements will you take?

3. What materials will you use?

4. What steps will you follow?

The variables in the plant experiment are the amount of acid (independent variable), length of root growth (dependent variable), and amount of water and light (controlled variables).

Check It Out

Once you have planned the experiment, you are ready to carry it out. As you experiment, you write down everything that you observe and measure. This information is called data.

Collecting and Analyzing Data (5)

In most investigations, scientists make observations and collect data to answer important questions. A good way to collect data is with a table.

Data Table and Graph

When you are done collecting information, you can analyze the data by counting the numbers in the table—and showing them in a graph, table, or chart. These methods visually present information.

In your science journal, answer the following questions based on the "Data Table and Graph."

1. What is the topic of the table?

2. Which grade level has the least number of students?

3. Which grade level has the greatest number of students?

Reporting Results (6)

You explain what your inquiry tells us when you report results using graphs, tables, and your Lab Experiment Sheet.

Teacher Presenting Data

In your science journal, answer the following question.

1. What else could you do to report the results of an investigation?

It helps when you write the results section concisely and in an orderly and logical way. Look at all the data you've collected. Figure out what relates significantly to your hypothesis and the predicted answer to the question you are trying to answer. This will help you to be clear and objective when describing your results.

Let's Practice