Cell Phone Radiation - How close is too close? (Focus: Scientific Explanations) Preview Close Preview

Welcome to iLabs! (1/15)

Remote Online laboratories (iLabs) are lab instruments located at universities around the world that you can use through the Internet, allowing you to carry out different experiments from anywhere at any time.

Before we get started, we would really appreciate it if you would answer a few questions that will help us understand how we can better help students learn science.

Please click on this link: Click Here and answer the questions to the best of your ability.

Cell Phone Radiation (2/15)

Now let's get started with your lab! The following sections will be a part of the assignment your teacher is giving you, and might be for points that count towards your class grade.

Have you ever heard rumors that using your cell phone too much can hurt your brain? Is it possible that using your cell phone could cause damage to your body? Is there anything you can do to protect yourself from possible harm?

Let's take a look at this CBS news report on cell phones and human health:

That seems pretty alarming!

What does the Center for Disease Control and Prevention (CDC) have to say about cell phone use? See what they say about how cell phone radiation works, and if your health is at risk when you use a cell phone.Cell Phone Radiation FAQs

After reviewing the information from both CBS and the CDC, answer the following question(s). Use the space provided to type your responses.

How does a cell phone use radiation to function?

Does the scientific community agree that cell phones pose a risk to your health? How do you know?

If you were a scientist, how would you test if cell phones cause health risks? What type of experiment might you design to figure out if you are hurting yourself with your cell phone?

How is Radiation Measured? (3/15)

Radioactivity is typically measured by a Geiger counter. Different models of Geiger counters detect and measure different kinds of radiation.


Geiger counters come in many forms, but they usually consists of three parts:


  1. Geiger tube – a gas-filled tube whose gas ionizes when charged particles or electromagnetic waves from a radioactive material pass through the gas. The ions create a signal that can be measured, allowing the Geiger counter to count the number of radioactive particles or electromagnetic waves that pass through the tube.

  2. Visual readout – a meter that keeps track of the number of radioactive particles or electromagnetic waves being detected by the Geiger counter.

  3. Audio readout – a meter that makes one “click” sound for each radioactive particle or electromagnetic wave counted by the Geiger counter. The clicks sound like this.

Let's Do an Experiment with Radiation (4/15)

The CBS News report seemed to say something very different from the Center for Disease Control and Prevention fact sheet, but both mention that moving your phone even a very short distance away from your body might be a good idea.

Why would that be the case?

To investigate this, you can design your own experiment to learn about how radiation moves through air. The instrument you will be using in this lab is located at the University of Queensland in Australia.


How does this lab work?

The lab equipment consists of:

  1. A Geiger counter
  2. A radioactive material (Strontium-90)
  3. A Circuit board that connects Geiger counter to the internet


The things that you can change in order to design an experiment are:

  1. The distances in millimeters from the strontium-90 source at which radiation can be measured. Radiation is measured in units of "particle counts", which means the number of particles emitted from the strontium-90 sample that were counted by the Geiger counter.
  2. The measurement time in seconds that each measurement of particle counts will last.
  3. The number of trials that will be conducted at the settings listed above.

What is strontium-90?

Research Question (5/15)

What are you trying to find out in this lab? What question are you trying to answer?

The last page gave you some information about the instrument you will be using to conduct an experiment about radiation. Now you need to develop the question you want to answer using this setup.

What is a research question? That is what your experiment is designed to answer. A “good” scientific research question is one that allows you to perform a test or experiment to show how your variables might be related. The results of the experiment will allow you to say something about how those variables are related. Your research question must be testable to make a strong statement about how the variables are related.

Your research question will guide your experimental design in the next step.

What is the independent variable in your remote labs experiment?

What is the dependent variable in your remote labs experiment?

Write your research question for your remote labs experiment.

Design Your Experiment (6/15)

Design your experiment by choosing values for the variables on the left. To learn more about each variable, click on the question mark icon next to the variable.

When you click "Run", the experiment will run on the instrument located at the University of Queensland in Australia.

Note that experiments are run one at a time, so you are being placed in a line or queue to run yours. If you don't want to wait, you can log out and come back later. Everything you have done up to now will be saved.

Radioactivity over Distance
Distance (mm)
Duration (s)
View your iLab Results (7/15)

Now let's take a look at the data you got from running your remote experiment.

You can review both your experimental design and the data you generated from your experiment in table form by clicking on the tabs below. Take a look at your data.

Do you notice any patterns in your data? If so, describe what those patterns are.

If you do not notice any patterns in your data, are there any changes you might make to your experimental design?

Analyzing your iLab Results (8/15)

Let's take a closer look at the results from your experiment.

By clicking on the tabs below, you can see the variables you chose for your experimental design, your data in table form, and a graph of your data.

Take a close look at the graph of your data in order to determine if there is a relationship between radiation (in particle counts) and distance. You can apply various best-fit functions to the graph in order to investigate the nature of this relationship, if there is one present.

Do you think a relationship exists between your two variables? What kind of relationship, and how do you know?

What is a Scientific Explanation? (9/15)

The State Representative in the CBS News Video introduced a bill that would require warning labels to be on cell phone devices, because they emit "electromagnetic radiation, exposure to which may cause brain cancer". This was described as common sense.

The experts on the Health Committee in the video, however, were not convinced. They want more than just common sense before recommending labels for cell phones - they want conclusive evidence.

Let's discuss what scientists do with experimental results. To convince other people that you have conclusive evidence that explains something about the phenomenon you are investigating, you need to develop something called a scientific explanation.

Scientific explanations are very different from everyday explanations. In an everyday explanation, you can state the answer to a question and support your answer with an opinion that is not always based on facts or knowledge.

A scientific explanation is different because it is not based on opinion. Scientific explanations are answers to questions that are based on real data or information that can be used to prove if something is true or untrue. Scientists create explanations to answer their research questions and convince other scientists that their answers are correct.


Scientific explanations include the following:

  • Claim - a statement or conclusion that answers a question
  • Evidence - measurable scientific data that is both appropriate and sufficient to support the claim.
  • Reasoning - a justification that shows why the data can be used to support your claim.
Did the CBS News video include anything that you would describe as a scientific explanation? Why do you think so?

Making a Claim (10/15)

The first step of creating a scientific explanation is to make a claim that answers your research question.

Take a look at an experiment below, and think about what the researcher can say about their results.


A researcher wants to know whether listening to different types of music when studying helps students get higher scores on their math tests. Students listen to classical, country, hip hop, or pop music while studying for a math test. In the control group, students do not listen to any music at all while they study. At the end of the experiment, students take their math test and the results show that students who listened to classical music got the highest scores on the math test out of all the groups.

What is a good example of a claim the researcher can make about her experiment?

Think about your research question, and the radiation experiment that you conducted. Can you think of a claim you might make about your findings?

Scientific Evidence and Reasoning: Part 1 (11/15)

Let's take a closer look at an example of scientific evidence and reasoning.

Watch the following video and answer the questions below:

The girl in the video makes the claim that her father is an alien. What evidence does she provide to support this claim?

Do you find the girl's reasoning convincing? Why or why not?

Scientific Evidence and Reasoning: Part 2 (12/15)

The little girl in the previous video made the claim that her dad is an alien. She presented evidence to support this claim, but the evidence she presents and the reasoning she used to link the evidence to her claim does not hold up well to closer examination.

What do we mean by that? Take a closer look:

Evidence: the dad is an alien because he speaks a “weird” language

Does the girl provide us with evidence we can see?In this case, she does not. "Weird" is difficult to measure because what is considered “weird” will be different for different people. This information is not scientific evidence, because it is not measurable data, so the girl cannot use it to support her claim.

Does the girl’s reasoning support her claim?In order for your reasoning to be convincing, you need to show that your evidence supports your claim. Since the girl’s evidence in this case is not real evidence, there is no way for her reasoning to work, either.

Evidence: the dad is an alien because he drinks green stuff

Does the girl provide us with evidence we can see?Technically, the girl’s dad is drinking something that is green in the video, so she could say that this information is evidence. However, this evidence does not support her claim, because a human can drink something that is green (like a spinach smoothie) and still be human.

Does the girl’s reasoning support her claim?The girl’s reasoning is that her dad is an alien because he drinks green liquid. As discussed above, the “green stuff” could just be an uncommon drink. In this example, the girl gives us evidence we can see, but it is not evidence that proves that the dad is an alien. In this case, the girl’s reasoning does not show how her evidence supports her claim.

Think of it this way: just because you state a fact does not mean that your fact will support any claim you choose. Imagine making the claim to your class that you can fly because you have arms. Most people in your class would disagree with your claim. Other students can see that you have arms, but they would probably say that just having arms does not allow you to fly. You can state something that is a fact, but that doesn’t mean you can use that fact as evidence for any claim you want.

Again, think back to the CBS News Video you watched earlier. The State Representative wants cell phones to carry labels warning that the electromagnetic radiation they emit may cause brain cancer.

What evidence was offered in the CBS News video that supports cell phones cause brain tumors? How was that evidence connected to the claim by reasoning?

Construct a Scientific Explanation (13/15)

Constructing a convincing scientific explanation can take some practice. Now that you know all of the parts (claim, evidence, and reasoning), try constructing a scientific explanation of your own.

Examine the following data table:


Write a scientific explanation that states whether any of the liquids are the same substance.

What does this mean in terms of your cell phone? (14/15)

At the beginning of this activity, you watched a CBS news report and read a fact sheet from the Center for Disease Control and Prevention. While they disagree about whether or not cell phones should have warning labels, both mentioned that moving your cell phone even a short distance away from your body might be a way to protect yourself from harm caused by radiation.


Now that you have completed the Radioactivity iLab, and know a bit more about the relationship between radiation and distance, you can apply what you have learned to the following question(s):

Based on your experimental evidence, do you think that the recommendation to keep distance between your cell phone and your body makes sense? Why or why not?

Create a one to two sentence warning to be put on cell phones based on what you have learned in this lab.

Using what you have learned about scientific explanations, create an explanation that describes why the label you proposed should put on cell phones. Be sure to include a claim, evidence, and reasoning.

Post-Survey (15/15)

Now that you have used iLabs to complete an assignment, we would like to again ask you some questions that will help us understand how we can better help students learn scientific concepts and how we can improve our product.

Please note, some of these survey questions are going to be very similar or even the same as questions we asked you before. We ask that you answer them honestly, as this will be a big help to us.

Please click on this link: Click Here and answer the questions to the best of your ability.