Designing an Arduino Geiger Counter

Nuclear engineers design and maintain systems that keep nuclear reactors safe. They create sensors to monitor conditions such as temperature and radiation, helping detect problems before they become dangerous. Events like the Chernobyl disaster show the importance of keeping reactors within safe limits. Nuclear engineers use these lessons to improve safety systems and protect people from harmful radiation through shielding, monitoring, and strict safety protocols.

After this activity, students should be able to:

• Define the types of nuclear radiation.
• Explain the effect of nuclear radiation on human well-being.
• Propose mechanisms and improvement plans to ensure healthy environmental conditions in classrooms.

Students should be able to:

• Create a line graph (this skill can be developed throughout the activity).
• Describe and analyze trends in graphs (this skill can also be developed throughout the activity).
• Add and subtract.
• Know the types of nuclear radiation.
• Have a basic understanding of physiology, especially how the human body repairs damage.
• Have knowledge of atomic structure.
• Have basic knowledge of the physical properties of materials.

You have been hired by the largest private environmental protection company in the world. The company wants to build a large apartment complex next to a nuclear reactor. There will be many families living in the complex, and the company wants to ensure they are safe from nuclear radiation. Your job is to ensure that there is a healthy level of background radiation. Your goal is to construct a Geiger counter, measure the background radiation, and create a report of your findings.

Let’s start with this question: How does nuclear radiation affect human health? (Let students offer answers; write student answers on board for all to see.) Radiation can damage living tissue. At low levels, the human body can usually repair the damage. But high levels of radiation exposure—especially over time—can lead to serious health problems such as cancer or organ failure. That’s why monitoring radiation is so important, especially in places where people will live and work. Now, not all radiation is dangerous. There’s something called background radiation—this is the natural radiation we’re all exposed to every day from things like the sun, soil, rocks, and even bananas!

Here’s the next question: What are normal and healthy levels of background nuclear radiation? (Let students offer answers; write student answers on board for all to see.) Typically, background radiation levels are low, measured in a unit called microsieverts per hour (µSv/h). For example, most places on Earth have background radiation levels of about 0.1 to 0.2 µSv/h. Anything significantly higher might require a closer look. Your job will be to take these kinds of measurements and compare them to what’s considered safe.

Which brings us to the final piece of the puzzle: How do we measure nuclear radiation? Radiation isn’t something we can see, smell, or touch. That’s why we use a device called a Geiger counter, a tool that detects particles emitted by radioactive materials. You’ll build your own Geiger counter, test it, and then use it to measure background radiation around our “reactor site.” You’ll analyze your data, write a report, and make a recommendation: Is it safe to build the apartment complex, or not?

This is real-world science. And real-world engineering. With real-world consequences. Your findings could influence the safety of hundreds of people. Are you ready to take on the challenge?

Background

Radiation is energy emitted from unstable atomic nuclei, and it comes in three main types. Alpha particles are heavy, slow, and easily blocked by paper or skin. Beta particles are lighter, travel faster, and can pass through skin but are stopped by materials such as aluminum. Gamma rays are high-energy electromagnetic waves that are extremely penetrating and can pass through the human body.

Radiation can damage cells, especially those that divide quickly, such as in the skin, bone marrow, and stomach. At low doses, the body can often repair this damage, but high doses or prolonged exposure can cause burns, radiation sickness, cancer, or organ failure. Not all radiation is harmful, though—radiation is used in medicine to detect and treat disease, sterilize equipment, and preserve food. These applications are safe when strict safety measures are followed.

Background radiation is the natural radiation we are exposed to every day from the sun, rocks, soil, and even food. Typical background radiation levels are low, around 0.1 to 0.2 microsieverts per hour (µSv/h). Knowing these levels helps put radiation risk into context. Because radiation cannot be seen, smelled, or touched, it must be measured with specialized instruments such as Geiger counters. These tools detect ionizing radiation particles and allow scientists and engineers to monitor exposure levels to ensure they remain within safe limits.

A Geiger counter is a handheld device used to detect and measure ionizing radiation, the kind of radiation that can remove electrons from atoms and potentially harm living tissue. It works by using a Geiger–Müller tube, which is filled with gas that becomes ionized when radiation passes through. Each time a radioactive particle or ray interacts with the gas, it produces an electrical pulse. The Geiger counter records these pulses, often as audible clicks and as a numerical reading on a display.

The more radiation present, the more clicks you hear and the higher the reading. Because radiation can’t be seen, smelled, or felt, Geiger counters are critical tools for monitoring radiation levels in environments such as hospitals, research labs, nuclear power plants, and even natural settings where radioactive materials are present.

Before the Activity

• Gather the materials needed by each group.
• Organize all the materials into trays or boxes (1 per group).
• Make copies of the Engineering Design Process Worksheet (PDF) (1 per student) or upload it to your LMS.
• Upload the Geiger Counter Instructions Presentation (PPTX) to your LMS or print a physical copy (1 per group).

DAY 1

Ask (20 min)

1. Introduce students to the activity by reading the Introduction/Motivation section. 
2. Put students into groups of 3-4.
3. Hand out one Engineering Design Process Worksheet (PDF)to each student.
4. Review the objective: You will use the engineering design process to design and build a Geiger counter prototype.
5. Optional: Review the steps of the engineering design process.
6. Review the constraints of the problem/challenge:

• • Must use Arduino parts.
  • Must measure radiation count per minute.

7. Pre-Activity Assessment Brainstorming: In their groups, have students engage in an open discussion, answering the question: How could radiation affect human health? Remind students that:

• • No idea or suggestion is "silly."
  • All ideas should be respectfully heard.
  • They should take an uncritical position, encourage wild ideas, and discourage criticism of ideas. Ask students how radiation could affect human health.

8. As a class, have them record their ideas on the board.
9. Quick Poll: Ask the class and tally their responses on the board: How can we measure background radiation to ensure healthy levels?

Research (25 min)

10. Show students this video: https://www.youtube.com/watch?v=s9APLXM9Ei8 (2:38 minutes).
11. Have students follow the directions in the Research section of their Engineering Design Process Worksheet (PDF).

• • Students write down a phrase, statement, or portion of dialogue that stands out to them.
  • Each student shares their chosen a phrase, statement, or portion of dialogue with their group.
  • Students write down what the quote “Every atom of uranium is like a bullet...” means to them.
  • Students quietly read the guided reading and answer the review questions. 

12. After students finish their reading and answer the guided reading questions, have a class discussion about the guided reading questions and clarify any misunderstandings.

• • What are the three types of nuclear radiation?
  • • Alpha particles: Heavy and slow; blocked by paper or skin.
    • Beta particles: Smaller and faster; can pass through skin but are stopped by materials such as aluminum.
    • Gamma rays: Energy waves; very penetrating and can pass through the human body.
  • How does radiation affect human cells?

Radiation can damage cells, especially fast-dividing ones like those in the skin, bone marrow, and stomach. The effects depend on the dose, duration of exposure, and which part of the body is exposed. Low doses may cause little harm, but high exposure can result in burns, radiation sickness, or cancer.

• • In what ways is radiation helpful to society?

Radiation is used to detect and treat diseases such as cancer, sterilize medical equipment, and preserve food. Scientists and doctors use it for many positive purposes while following strict safety measures.

Imagine (15 min)

13. Show the following two videos:

• • What tools measure radiation? https://www.youtube.com/watch?v=cwOPGfLkB7w (1:44 minutes).
  • Why do Geiger counters click? https://www.youtube.com/watch?v=qtvz8lH5zhk (3:07 minutes).

14. Have students complete the Imagine section of their Engineering Design Process Worksheet (PDF), where they brainstorm ideas with their group and then sketch their ideas and designs in their worksheet.
15. If any class time remains, have students begin to review the Geiger Counter Instructions Presentation (PPTX).

DAY 2

Plan (15 min)

1. Give each group a Geiger Counter Instructions Presentation (PPTX) or make it available digitally.
2. As a class, go over each part so the students are familiar with the components and functions of the Arduino Geiger counter.
3. Have students work with their groups on the Plan section of their Engineering Design Process Worksheet (PDF).

• • Groups review the Geiger Counter Instructions Presentation (PPTX).
  • Each group makes a drawing of their final Geiger counter design.
  • Each group lists the materials that they will need for their design.

Create (30 min)

4. Using the Geiger Counter Instructions Presentation (PPTX), have each group build their planned Arduino Geiger counter. 
5. As students complete their Geiger counter, have students bring their design to your computer and download the Geiger Counter Arduino Sensors Code (PDF)onto their Arduino through the Arduino IDE application.

This is the final product: a functioning Geiger counter.CopyrightCopyright Matthew Reis

Preparing to Test (15 min)

6. Have students discuss which locations in the school will have the highest background radiation
7. Allow students to search online resources to investigate normal background radiation.
8. Have students make their hypothesis and write it in their Engineering Design Process Worksheet (PDF).

DAY 3

Test (60 min)

1. Allow students to take their Arduino to different locations in the school and collect data for 10-15 minutes.
2. Have students enter their results in Data Table #1 in their Engineering Design Process Worksheet (PDF).
3. Have students answer the questions in the Test section.
4. Homework: Have students transform their Data Table #1 results for the different locations to make line graphs and draw conclusions.

DAY 4

Improve and Retest (60 min)

1. Have students make changes to their Geiger counter prototype based on what worked and what did not work during testing.
2. Have students retest their Geiger counter prototype in the same locations around the school for the same times.
3. Have students record their results in Data Table #2.
4. Have students answer the questions in the Improve section of their Engineering Design Process Worksheet (PDF).
5. Homework: Have students transform their Data Table #2 results for the different locations to make line graphs and draw conclusions and then answer the Reflection Questions in the Engineering Design Process Worksheet (PDF).

DAY 5

Summary (30 min)

1. Have students draft a Radiation Report that includes the following:

• • Background research (use answers from reading check)
  • Challenge question/objective
  • Hypothesis
  • Methods
  • Graph
  • Analysis in CER paragraph format that states whether their hypothesis was supported or rejected with justification using numerical evidence
  • A discussion that includes improvements and further research ideas

Conclusion (30 min)

2. Have students design a poster that could be shared on campus that teaches the community about the background radiation at different locations at school and the health effects of nuclear radiation. Include the strengths and limitations of the Geiger counter.
3. If time, have students present their final reports and posters based on the Student Rubric (PDF). 

A final stand with functioning Geiger counter and trifold posters.CopyrightCopyright Matthew Reis

Pre-Activity Assessment

Brainstorming: In small groups, have students engage in open discussion. Remind them that no idea or suggestion is "silly." All ideas should be respectfully heard. Take an uncritical position, encourage wild ideas, and discourage criticism of ideas. Ask students how radiation could affect human health. As a class, record their ideas on the board.

Quick Poll: Before the activity begins, ask the class a question and tally their responses on the board. Ask: “How can we measure background radiation to ensure healthy levels?”

Activity Embedded Assessment

Worksheet/Pairs Check: Have students work individually or in pairs on the Reading Check. After they finish, have them compare answers with a peer or another pair, giving all students time to finish the Engineering Design Process Worksheet (PDF).

Hypothesize: Have students hypothesize and record their hypotheses for the following questions:

• What will be the background radiation at the school?
• What areas will have the most background radiation, and why?

Post-Activity Assessment

Problem-Solving and Reflection: Once their data is collected, have students answer the Reflection Questions in the Engineering Design Process Worksheet (PDF):

• What is the relationship between location and background radiation?
• What would happen to a person who lived next to and was exposed to nuclear radiation?
• How could you construct an infrastructure to contain nuclear radiation?

Radiation Report: Students use the data from their graphs to construct a Radiation Report explaining the relationship between location in the school and background radiation.

The most common problem is that the students connect the jumpers incorrectly. It’s best to have an Arduino already assembled as a model or assign a teaching assistant. The teaching assistant could be a student that comes before class and assembles the Arduino or assembles the Arduino quickly in class and can then support other students.

The other tip is to program the Arduinos outside of class. If you program them during class you can have problems.

For more advanced students, have them choose TWO UN sustainability goals and justify how this activity fulfilled them (https://sdgs.un.org/goals). Note: You must select a specific criterion within the UNSG.

Murchison, Joseph. Arduino DIY Geiger counter. 24 June 2011, www.instructables.com/member/Josehf+Murchison. Accessed 5 May 2025.