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Lesson Overview
Sometimes inventors discover something they weren't intending. That was the case with Wilson Greatbach. He was doing an experiment with an electronic oscillator and used a wrong component. The plans called for a 10,000 ohm resistor and he accidentally used a 1,000,000 ohm resistor. Instead of a tone he had expected, the circuit made a "blip" noise ever second of so. From this accident the idea of a pacemaker was born. Thereafter Wilson's circuit became the mainstay of all implanted pacemakers for decades. In this series of explorations students experiment with Wilson's circuit, learn about resistance in electronics, make circuits with liquid conductors, and are invited into the world of electronics technology
Read
Engineers read a great deal--technical manuals, resource pages, descriptions of materials, and reports. It's important for students to associate reading with STEM. Students can engage in reading about Greatbatch's the "Mistake That Saves Lives" here.
Respond to the Video and Story
Prompt students to respond to the story. Nudge their questions and responses: What surprises you about this story? What kind of a scientist/inventor/engineer was Wilson Greatbatch? What is a pacemaker? What components was he using and why did the one change make such a big difference? How could we repeat his experiment?
For more information about how students can read the story go to Reading LA STEM Stories.
Students should record their questions, observations and procedures in a notebook. See directions for the STEM Notebook here.
2. Choose any or all of the following exploration options:
a. Building the Greatbatch circuit: Students use a cardboard diagram, springs and components to assemble a circuit like Greatbatch's. They can create the original sounds with a 10,000 ohm resistor and then insert a 1,000,000 ohm resistor to make a pacemaker.
Pacemaker shown at left.
b. Testing resistance in the circuit. Students can make their own resistors by using a pencil lead or with by drawing a resistor on a piece of card stock.
Packaged resistor shown at left.
c. Making a circuit using a liquid conductor. By combining graphite, rubbing alcohol, and white glue, a conductor can be made and various values of resistance can be painted onto card stock and then tested.
Shown here is painting the liquid conductor to connect a foil circuit with an LED.
3. STEM Challenge for Students
Students are invited to make circuit boards using foil that is lightly glued to card stock. The unwanted material can be cut and peeled to make a circuit trace. Components such as resistors, leds, and switches can be added by using a liquid conductor to make working circuits. Students design boards, construct circuits, and test their creations.
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