Source: https://mokxi.com/teachers/plans/build-lie-detector Updated: 2026-11-11 Lesson plan # Build a science fair lie detector lesson plan Skin response and heart rate against a calm baseline: a science demo of the stress response, not a real lie detector. 2 chapters, 3 lessons, about 2 hours, on the Arduino Uno R3. Every lesson runs in the browser, with nothing to install. Start a class from this course The unit ## Objectives and materials ### By the end, students can - Read skin conductance in real units, then measure it against a calm baseline. - Add a heart rate sensor and turn both changes into one stress bar. ### Materials for the whole unit - Arduino Uno R3 - Full-size breadboard - Galvanic skin response sensor - LED bar graph, 10 segments - MAX30102 pulse oximeter - Pushbutton - Resistor x 10 Every part is already on the simulator’s bench, so there is nothing to buy or hand out. The counts are the most any one lesson uses, if you build it on real breadboards too. Chapter 1. About 1 h 20 min ## The skin Read skin conductance in real units, then measure it against a calm baseline. Lesson | Time | What students do Read the skin A galvanic skin response sensor and a ten-segment bar graph. How skin conducts, how a formula turns a reading into microsiemens, and why sweatier reads lower. | 40 min - A science demo, said plainly - From a reading to microsiemens - Sweat a little - Hands off A calm baseline Measure ten calm seconds first, then show only the change from them. Why a change from someone's own baseline means more than any single number. | 40 min - Ten quiet seconds - The baseline - A surprise - Back to calm ### Materials - Arduino Uno R3 - Full-size breadboard - Galvanic skin response sensor - LED bar graph, 10 segments - Pushbutton - Resistor x 10 ### Check for understanding Each student finishes "A calm baseline" on their own, without opening the hints. The simulator checks 4 of its 4 steps as they go. Then ask each one to explain, in a sentence or two, the last thing it asked of them: "Back to calm". Chapter 2. About 40 min ## The heart Add a heart rate sensor and turn both changes into one stress bar. Lesson | Time | What students do Add a heartbeat Finish the science fair build: a MAX30102 heart rate sensor joins the skin sensor, and both changes from the baseline fill the stress bar. | 40 min - Two signals - A racing heart - One score - Finger off ### Materials - Arduino Uno R3 - Full-size breadboard - Galvanic skin response sensor - LED bar graph, 10 segments - MAX30102 pulse oximeter - Pushbutton - Resistor x 10 ### Check for understanding Each student finishes "Add a heartbeat" on their own, without opening the hints. The simulator checks 4 of its 4 steps as they go. Then ask each one to explain, in a sentence or two, the last thing it asked of them: "Finger off". Your class ## Teach this unit as a class Start a class from this course and its 3 lessons are assigned in one go, in order. Students join with a six-character code or printed login cards, and each one’s work comes back to you. The class tools are free for 30 days for one class of up to 20 students, with no card. The lessons themselves are free either way. Start a class from this course See the demo class More units ## Other lesson plans Electronics basics 20 lessons, about 10 h. Embedded on the Arduino Uno 16 lessons, about 12 h. Embedded on the ESP32-C3 13 lessons, about 11 h. Embedded on the Raspberry Pi Pico 7 lessons, about 6 h. Build your own fight stick 5 lessons, about 4 h. Embedded on the STM32F411 6 lessons, about 6 h. C++ on a board 13 lessons, about 10 h. Digital logic and memory 4 lessons, about 4 h. Interactive devices on the Uno 9 lessons, about 8 h. From gates to a computer 23 lessons, about 16 h. Build a claw machine 8 lessons, about 6 h. Every unit All the courses as ready-made units, on the teachers page.