How to Turn a Question Into an Experiment

A lot of science starts with a question.

Why does one plant grow faster than another?

Does temperature affect how quickly something dissolves?

Does the amount of sunlight affect plant growth?

But asking a question is only the beginning.

To turn a question into an experiment, I need to figure out what I can actually change, measure, and test.

Start With a Question

A good experiment begins with a question that can be investigated.

For example:

Does the amount of sunlight affect how tall a plant grows?

This question gives me something specific to investigate.

It is much easier to design an experiment when the question is specific instead of being something extremely broad like:

What makes plants grow?

The more specific the question is, the easier it becomes to decide what data I need.

Find the Independent Variable

The next step is figuring out what I am going to change.

In the plant example, I could give different plants different amounts of sunlight.

The amount of sunlight would be the independent variable because it is the factor I am deliberately changing. (delsiegle.education.uconn.edu)

For a good experiment, I usually want to change one main variable at a time.

That makes it easier to understand what caused the results.

Decide What to Measure

Next, I need to decide what I am going to measure.

If I change the amount of sunlight, I could measure the height of each plant.

Plant height would be the dependent variable because it is the result I am observing and measuring. (delsiegle.education.uconn.edu)

This gives me actual data instead of just an observation like "Plant A looks healthier."

I could record the height of each plant every few days and compare the results.

Think About What Should Stay the Same

There are probably many other things that could affect the experiment.

For the plants, I might want to keep these the same:

• Type of plant
• Type of soil
• Amount of water
• Size of the container
• Amount of fertilizer
• Temperature

These are controlled variables.

Keeping important conditions consistent helps make the experiment a fair test. (ecuip.lib.uchicago.edu)

If I changed both sunlight and water at the same time, I wouldn't know which one affected the plants.

Make a Prediction

Before starting the experiment, I can make a prediction.

This is often called a hypothesis.

For example:

If plants receive more sunlight, then they will grow taller.

The prediction gives me something to test.

It also means I can compare my prediction with what actually happens.

My hypothesis doesn't have to be correct.

That's one of the interesting things about science.

An experiment can give me a useful result even if my original prediction was wrong.

Plan the Data

Before starting, I should also decide how I am going to collect my data.

For the plant experiment, I could measure each plant's height once every three days.

I could record the measurements in a table.

For example:

| Day | Plant A | Plant B | Plant C |
|---|---:|---:|---:|
| 0 | 5 cm | 5 cm | 5 cm |
| 3 | 6 cm | 7 cm | 5 cm |
| 6 | 8 cm | 10 cm | 7 cm |

Having a plan makes the experiment easier to organize and gives me data that I can actually compare.

Run the Experiment

Once everything is planned, I can perform the experiment.

This is where I collect the actual data.

It's important to follow the same procedure each time.

If something unexpected happens, I should record it instead of ignoring it.

Unexpected results can sometimes reveal problems with the experiment or lead to new questions.

Look at the Results

After collecting the data, I can look for patterns.

Maybe the plants receiving more sunlight grew faster.

Maybe there was very little difference.

Maybe the results were completely different from what I predicted.

The data helps me decide what the experiment actually showed.

I shouldn't change the results just because they don't match my hypothesis.

From One Question to Another

One of my favorite things about experiments is that they can create new questions.

Suppose I discover that sunlight affects plant growth.

That could lead to another question:

Does the color of the light affect plant growth?

Then I could design another experiment.

Science can keep going like this.

One question can lead to an experiment, which leads to results, which can lead to an even better question.

Reflection

I used to think an experiment mostly meant following a set of steps and seeing what happens.

Now I understand that the planning before the experiment is just as important.

I need a question that I can test, a variable to change, something to measure, and other important conditions to keep the same.

The basic process is:

Ask a question → make a prediction → plan the experiment → collect data → analyze the results → ask what comes next.

That's how a simple question can turn into an actual scientific investigation.