Lesson: How Does a Robot Work?

Contributed by: GK-12 Program, Computational Neurobiology Center, College of Engineering, University of Missouri

Photo shows a bi-pedal robot that looks like a person in a spacesuit and helmet.
How does a robot work?
Copyright © Wikimedia Commons http://commons.wikimedia.org/wiki/File:Robot_asimo_cropped.jpg


This lesson introduces electricity, batteries and motors using a LEGO® MINDSTORMS robot. The associated activity guides students to build a simple LEGO set-up and see the practical implementation of the concepts discussed. Before studying the importance of electricity and how it is crucial for robot movement, students consider various electronic devices they use in their daily lives so that they have an understanding of how engineers use electricity to power such devices, including robots. The lesson starts with a brief introduction to electricity and the working of batteries. A simple electrical circuit demonstration highlights how three basic electrical devices (buzzer, LED and motor) are driven by electricity. An activity at the end further reinforces these concepts. **Note: This lesson uses the retired LEGO NXT robot which is no longer available for purchase.
This engineering curriculum meets Next Generation Science Standards (NGSS).

Engineering Connection

Students see how an electrical circuit can drive an electric device, including the concept of electrical energy in a battery being converted to light (LED), sound (buzzer), and mechanical energy (movement of motor). In the activity, students are asked to design a program to perform a particular task which utilizes programming skills and engineering design. Through this lesson and activity, students build a basic understanding of how robots work and would get an appreciation of how engineers in the real world build such devices.

Learning Objectives

After this lesson, students should be able to:

  • Explain that a battery stores energy that can be used as electricity to make a motor turn.
  • Explain that electrical circuits convert chemical energy stored in the batteries to other forms of energy such as light, sound and mechanical energy.
  • Explain how electric motors are one way to make robot parts move.

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Middle School Lesson

Educational Standards

Each TeachEngineering lesson or activity is correlated to one or more K-12 science, technology, engineering or math (STEM) educational standards.

All 100,000+ K-12 STEM standards covered in TeachEngineering are collected, maintained and packaged by the Achievement Standards Network (ASN), a project of D2L (www.achievementstandards.org).

In the ASN, standards are hierarchically structured: first by source; e.g., by state; within source by type; e.g., science or mathematics; within type by subtype, then by grade, etc.

  • Make observations to provide evidence that energy can be transferred from place to place by sound, light, heat, and electric currents. (Grade 4) Details... View more aligned curriculum... Do you agree with this alignment?
  • Apply scientific ideas to design, test, and refine a device that converts energy from one form to another. (Grade 4) Details... View more aligned curriculum... Do you agree with this alignment?
  • The development of technology is a human activity and is the result of individual and collective needs and the ability to be creative. (Grades 6 - 8) Details... View more aligned curriculum... Do you agree with this alignment?
  • Describe how new technologies have helped scientists make better observations and measurements for investigations (e.g., telescopes, electronic balances, electronic microscopes, x-ray technology, computers, ultrasounds, computer probes such as thermometers) (Grade 5) Details... View more aligned curriculum... Do you agree with this alignment?
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Electricity is all around us and we use it daily at home, school and work. In today's lesson you will learn about the concept of electricity and how it is used to power a variety of devices using electrical circuits. Then we'll make an engineering connection through an activity that uses the concepts for the design of a ball shooter, in which you'll do some basic programming with LEGO robots.

Lesson Background and Concepts for Teachers

Use the How Does a Robot Work? Presentation (a PowerPoint file) to present the lesson content to students. A separate PowerPoint file is provided for the associated activity, NXT Ball Shooter. Refer to the guidance below for how to use the slides. In advance, make copies of the pre/post assessment sheets, which are embedded in the PowerPoint file. Also prepare for a short demo that uses a breadboard; see materials list, below. Begin by handing out the pre-assessment sheet on slide 2 and asking students to fill them out.

How does a Robot work? (Slides 1-13)

  • (Slide 2) Four pre-assessment questions.
  • (Slides 3-6) Introduce students to the concept of electricity, electric current and batteries.
  • (Slide 7) Explain what an electric circuit is and show the "Create a Lemon Battery" video (6:47 minutes) using the provided link. The video shows the usage of a lemon as a battery and how it forms an electric circuit to light an LED. Explain how the electric charge flows from one terminal of the battery to the other, as shown in the video.
  • (Slide 8) Explain how a circuit can be open or closed and and that a circuit must be closed for current to flow.
  • (Slide 9) Relate the concept of electric circuit and current flow to explain how the battery produces electricity.
  • (Slides 10-11) Show a 10-minute demo. Before class, prepare the breadboard circuit shown on slide 11 using the Materials List for Demonstrations below.
  1. Obtain the components and connect them on a breadboard, as shown on slide 11.
  2. Refer to the following YouTube videos to learn the basics of breadboards (video 1 and video 2).
  3. If you are not familiar with electric circuits, watch this detailed video clip (rmvb) to learn how to assemble the electric circuit on the breadboard. The clip provides narration with step-by-step instructions.
  4. Use red wires to connect all the positive terminals of the devices and black wires to connect all the negative terminals. When storing the circuit, leave the negative terminal of the battery unconnected.
  • (Slides 12-13) The LEGO robot battery passes power to the robots' motor.
  • (Slide 13) Note that the internal motor configuration of a LEGO robot is similar to the other motor students worked with.
  • Next, conduct the NXT Ball Shooter associated activity to give students an opportunity to explore how electricity is used in a robot.

Materials List for Demonstrations

Breadboard components required for the demonstration

  • breadboard, such as from Radioshack
  • Rectangular High-Brightness Blue LED Lamp, such as from Radioshack
  • 76dB Piezo Electric Buzzer, such as from Radioshack
  • DC motor (1.5-3V), such as from Radioshack
  • hook-up wire 22AWG (Note: Buy "solid" wire, not "stranded"), such as from Radioshack
  • CR123 3V Battery, such as from Radioshack

LEGO MINDSTORMS NXT kit with software: You need at least one set per 2-3 students for the activity. A single one can be used to demonstrate to the class in the lesson.

Associated Activities

  • NXT Ball Shooter - Students explore how electricity is used to make a robot arm move.

Lesson Closure

The goal is to ensure the students understand the concept of electricity, electric circuits and how electricity powers LEGO NXT robot motors. Make the point that a battery is the power source used to drive motors in the LEGO robots and the motor in turn makes the robot move. Mention real-life examples like how cell phones are powered on only after charging their batteries. Conclude by making sure students understand that electrical devices typically convert electrical energy to other forms such as light (LED), sound (buzzer) or motion (motor).



Pre- Assessment Quiz

Before starting the lesson, administer the four-question pre-assessment quiz (slide 2) in which students write down their understanding of the basics related to electricity, batteries, motors, etc. Review their answers to gauge their base understanding of the subject matter.

Post-Assessment Quiz

After students finish the associated activity, administer a four-question post-asssesment quiz (slide 16) to make sure they understand how a robot works. After they have finished writing their answers, discuss the answers as a class (slide 17). Review student answers to gauge their individual comprehension of the subject matter.


Carr, Karen. "Electricity." Kidipede - History for Kids. Accessed 10/26/2011. http://www.historyforkids.org/scienceforkids/physics/electricity/

Hurbain, Philippe. NXT Motor Internals. Accessed 10/26/2011. http://www.philohome.com/nxtmotor/nxtmotor.htm

Physics4Kids.com: Electricity and Magnetism: Introduction. Accessed 10/26/2011. http://www.physics4kids.com/files/elec_intro.html


Kalyani Upendram; Ajay Nair; Satish Nair


© 2013 by Regents of the University of Colorado; original © 2010 Curators of the University of Missouri

Supporting Program

GK-12 Program, Computational Neurobiology Center, College of Engineering, University of Missouri


This curriculum was developed under National Science Foundation GK-12 grant no. DGE 0440524. However, these contents do not necessarily represent the policies of the National Science Foundation, and you should not assume endorsement by the federal government.

Last modified: November 16, 2018