Exploring Science:
Activities Using
LEGO® Robotics
Grades 3-5
©Technically Learning 2010-2012
TABLE OF CONTENTS
ACTIVITIES
1. INTRO TO THE LEGO™ KITS: GRAVITY POWERED CAR ................................................................................ 3
2. RUBBER BAND POWERED CAR ............................................................................................................ 5
3. HAND POWERED CAR ...................................................................................................................... 6
4. HAND POWERED HILL CLIMB .............................................................................................................. 7
5. TEACHER LED: DEMONSTRATE NXT PROGRAMMING .................................................................................. 8
6. DRIVE FORWARD .......................................................................................................................... 11
7. ROBOTIC ENERGY SAVERS ............................................................................................................... 13
8. SUNLIGHT REFLECTIONS ................................................................................................................ 14
9. ROBOTIC MUSIC ........................................................................................................................... 16
10. ROBOTIC ECOSYSTEMS AFFECTED BY POLLUTION ................................................................................. 17
11. ULTRASONIC MEASUREMENTS ......................................................................................................... 18
12. MEASUREMENT OF SEA LEVEL RISE ................................................................................................... 20
13. CYCLICAL SYSTEMS ..................................................................................................................... 21
14. WIND POWER ............................................................................................................................ 23
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1. INTRO TO THE LEGO™ KITS: GRAVITY POWERED CAR
Goal: To win a competition by having your un-powered car roll the farthest after coasting down
the ramp.
Main
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Themes:
Gravity as a means of propulsion
Investigating the LEGO™ kit
Building familiarity and confidence with construction
Theory: Gravity pulls the car the ramp, and it gains speed as it rolls down. Then it rolls as far as
it can, until friction eventually stops it.
Pre-Activity Preparation: Build a gentle-incline ramp. Cardboard pieces taped together work
well. The ramp only needs to be 6 or 8 inches tall to make this work. Make the ramp shorter if
you don’t have much room for the rovers to roll.
Ramp:
Construction Tips:
 Make sure that the students build a vehicle of some sort. While a single wheel rolled down
the ramp could win, in theory, that won’t help them develop building skills.
 The NXT computer brick is not required since there is no need to power the car. The extra
weight won’t make the car roll more or less, even if you add it.
Discussion Questions:
 Do the cars roll further when released higher up the ramp? Why?
o Yes. The car has longer on the ramp to gain more speed. Put in another way,
gravity has more distance to pull the car down.
 How would your car be affected by the weaker gravity on Mars or the Moon?
o Since the gravity on Mars is weaker than on Earth, the car builds up less speed and
would travel slower on Mars.
 How would your car be affected if it were on different surfaces, such as dust and sand?
o The loose dust and sand causes more friction, which slows the car down more than
a smooth hard surface.
 Was there a certain type of car that went further than others? Any noticeable patterns?
o There may be no pattern. Patterns may only emerge after each car has been run 5
or so times, and the distances are averaged.
 Next, have them do 5 runs down the ramp and record the distance their rover travels for
each.
o Why are the distances different from run to run for the same car?
 Many factors that affect the distance can change slightly from run to run: air
currents, how it is released, dust bunnies, etc.
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o
Average the distance for each car across the 5 runs. Compare the cars’ average
distances. Are there any patterns for what types of rovers go the furthest?
 Cars with bigger wheels tend to go a little further
 The weight of the car doesn’t influence the distance
Activity Variations (optional):
 Let the car roll down the ramp 5 times with rubber treads on your wheels. Then do 5 runs
with no rubber on the wheels (just the hard plastic hub). Record the distance that the car
travels for each run. Average the distances for the rubber wheels and the non-rubber
wheels.
o Which type of wheel rolls further? Why?
 The wheels without rubber should roll slightly further. The rubber wheels
produce slightly more friction because the rubber slightly deforms at the
point touching the ground. This extra friction causes the rubber wheeled
rover to slow down and stop sooner than the non-rubber wheeled car.
 This activity could be repeated on different surfaces, such as on top of cardboard, on
carpet, linoleum, or pavement outside.
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2. RUBBER
BAND POWERED CAR
Goal: To build a rubber band car that travels the farthest.
Main
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Themes:
Energy storage within the rubber band
Converting stored energy to motion
Testing variables
Theory: The rubber band used in this experiment acts like a spring storing energy as you
stretch it. When you let go of the car, the rubber band tries to retract to its un-stretched size.
As it contracts, the rubber band turns the axle that it’s wrapped around. Turning the wheel’s
axle accelerates the car forward. Transferring stored energy into motion is something that
happens all around us: electricity stored in batteries moves remote controlled cars, gasoline
(stored energy) powers automobiles, springs on a pogo stick, etc.
Construction Tips:
 There are many different styles of car that will work, and many ways of winding the
rubber band around the axle. Pictured is just one option, and the students should be
encouraged to try out different designs.
Picture of a potential car on the left. Shown on the right is how to “wind” up this car.
Discussion Questions:
 What factors affected the car’s performance the most?
o Changing the tires?
o Winding it up more?
o Adding or subtracting weight?
 Did running the car on different surfaces (tile floor, carpet) have an effect on how far it
traveled?
Questions? Comments?
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3. HAND
POWERED CAR
Goal: To build a motorized LEGO™ car. Power for the car will come from a hand-cranked
generator.
Main
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Themes:
Motors and generators
Transfer of energy
Gaining familiarity with different LEGO™ parts
Theory: The energy that is used to turn the hand crank is converted into electricity by the
generator. The electricity travels down the wire to the motor that powers the car. The motor
converts the electricity back into movement.
A generator could be thought of as the opposite of a motor. The motor uses electricity to
produce rotational motion, while the generator uses rotational motion to produce electricity.
Construction Tips:
 You can base your car off the cars the students built for the rubber band car
 Use the longest wire in the kit, so that you have a bit more freedom driving the car
 Build a crank for the generator
 A simple car and crank system is shown below:
Discussion Questions:
 Could you let the car coast without having the crank spin wildly in your hands?
 Was it easy to follow the car around? Could you drive the car so fast that you had trouble
keeping up?
 Was easier to turn the crank when the car was driving on smooth surfaces? Was it harder
on bumpier or carpeted surfaces?
Questions? Comments?
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4. HAND
POWERED HILL CLIMB
Goal: To build a hand powered car that climbs the steepest hill.
Main
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Themes:
Motors and generators
Transfer of energy
Friction and center of gravity
Theory: The motor theory from the previous exercise applies. This exercise focuses on the
friction between the wheels and ground, as well as the center of gravity of the car. If you use
a wheel without enough friction (which is also sometimes referred to as ‘traction’) then the
car won’t be able to climb the hill. If your car is too top heavy, then it might tip over when
the hill gets steeper.
Construction Tips:
 There are many objects to re-purpose as a hill: a shelf, small white board, tilted desk, etc.
 Give the students time to practice on different angle hills.
 At the end of the period, hold the competition to see which car can climb the steepest hill
o Place one end of the board (or shelf, etc) on a small stack of books so that it’s not
too steep
o Let all the cars try the hill. Any car that can climb to the top moves on to the next
round.
o Add books to make the hill steeper, and repeat as needed until someone wins.
Discussion Questions:
 Was it harder to turn the crank as the hill got steeper?
o It should be harder as the car has to overcome the force of gravity to climb the hill
 Did you car tip over at all?
o The lower the mass of the car, the less likely it will be to tip over
o Race cars, for example, have very low centers of gravity to help keep them stable
in high speed turns
Questions? Comments?
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5. TEACHER LED: DEMONSTRATE NXT PROGRAMMING
Goal: Show students the basics of NXT programming.
Background: The NXT is the computer for the rover. The NXT also provides power to the
motors and sensors.
Programming overview:
 NXT programming uses icons to represent actions your robot can take.
Move – Choose these icons to activate motors
Record/Play – record movements and then replay them
Sound – play sound files or tones
Display – Change the display on your robot (i.e. show an image or text)
Wait For – Wait for a change in light readings, a distance to an object, or a button push
Loop – use loops to create indefinite behaviors
Switch – choose from 2 different actions (i.e. do one action if the touch
sensor is pressed in, do a different action if the touch sensor is not pressed)
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
Each programming icon you select from the menu panel on the left of the screen has
many properties you can edit. These properties are reflected on the icon.
Motors:
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OR
Port: On this “Move” icon, the red arrow is
pointing at the letters (C,B) which indicate which
motors will be turning.
Duration: The purple arrow shows how long the
motors will be turning. In this case the “infinity”
symbol is shown because the motors are set to
turn an unlimited amount.
Power: The blue arrow points to the power level.
On this icon, it is shown at about ¾ power.
Direction and Steering: The yellow arrow
shows the direction the motors are set to turn.
This icon shows that the motors will move
forward.
There are 2 ways to tell the motors to turn the wheels:
 To tell the rover to turn to the right, the easiest
way is to turn on the left motor (C) while telling
the right motor (B) to stop. This causes the left
wheel to rotate, turning the rover to the right. A
slight variation is to turn on the left motor going
forward, while the right motor is on going
backwards. This causes the rover to rotate to the
right in place. This is similar to how some
vehicles, such as tanks and wheelchairs, navigate
and turn.
 Or you can turn on both motors (C and B) and
use the steering slider in the motor properties to
tell it to turn right.
Distance Sensor:
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Port: On this “Wait for Distance” icon, the red
arrow points to the port number that the distance
sensor is connected to, in this case, port 1.
Wait ‘Until’: The blue arrow points to a visual
representation of the distance selected. In this
case the slider is show about half full, indicating
that it will wait for an object to be about half of
the distance that the sensor can detect. This is a
value of 50 inches.
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Light Sensor:
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Port: On this “Wait for Light” icon, the red arrow
points to port number for this sensor.
Wait ‘Until’: The purple arrow points to a picture
of the value of light the NXT will wait for. In this
case, it shows the bars about half full, indicating
that the robot will be waiting for a light level
about halfway between dark and very-bright.
Function: The purple arrow points to a image
indicating that the light sensor will generate its
own light. (This is useful for reflecting off of
nearby surfaces to sense them. See activity 8)
String the icons together in linked in a chain to form more complex series of behaviors
for your robot.
The NXT will execute each command or action in order.
When the NXT gets to the end of the program, it is done executing commands, but the
motors will stay on unless you explicitly stop them.
Construction Demo:
 Use a wire connector to hook up a motor to one of the NXT outputs (use either the A or C
ports on the NXT)
 Attach a wheel to the motor to make the spinning more visible
Sample Code:
 Write a simple program that turns on the motors for 5 seconds.
o The code would look like this:

Download this program to the NXT and demonstrate that it causes the motor to turn on
and spin the wheel.
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6. DRIVE
FORWARD
Goal: Build a motorized robot that drives forward.
Main Themes:
 Robot construction
 NXT Programming
Robotics Theory: Generally, mobile robots are designed with 2 motors, one on each side (each
motor is paired with a wheel). This robot maneuvers in the way a wheel chair or tank would.
It’s actually very different from how a passenger car or truck moves. This design allows the
rover to turn easily by having only one motor on, and drive in a straight line by having both
motors on. It can also pivot in place by turning on one motor forward and one motor
backwards.
Construction Tips:
 The most basic LEGO™ robot consists of:
o 2 motors under the back of the NXT, with wires connected to the lettered ports,
which provide power output.
o Reinforce the motors (so they stay on the car) with LEGO™ strips connecting both
motors
o Attach wheels to the motors using axles
o A front wheel is not necessarily needed
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Sample Code:
This program tells the rover to:
 Turn on motors A and C in the forward direction for a timed amount (e.g. 3 seconds)
Discussion Questions:
 How would you make your car go faster? How about slower?
o Use wheels that are larger in diameter to make the car go faster.
o Use wheels that are smaller in diameter to make the car go slower.
o Use the “speed slider” in the programming interface to change the motor’s speed.
 Did your car go in the direction you expected? Why or why not? What did you do to
correct it?
o “Forward” is a particular direction for the motors, and turning the motors around
will make the car go in the opposite direction.
o If the car was veering off in one direction, check that nothing (i.e. a wire) was
blocking a tire from spinning freely.
Activity Variations (optional):
 Make your car rotate in place
Questions? Comments?
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7. ROBOTIC ENERGY SAVERS
Goal: To build a robot that powers down when the lights turn off. This can be a car that stops
running when the lights dim (as if it were a solar powered car). It could be a robot flower that
closes when sun sets. It could be a merry-go-round that stops when the lights go off. This unit
serves as introduction to sensors.
Main
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Themes:
Introduction to sensors
Light sensors
Programming to wait for a change in the environment
Robotics Theory: Sensors allow the rover to gain information about its surroundings. The
program can then make decisions based on this information. The LEGO™ light sensor
measures how much light there is ranging from complete darkness (a value of 0) to a strong
light (point the light sensor at the sun to see a high value, perhaps 70 or 80). The sensor has
a range from 0 to 100.
Construction Tips:
 You can re-use the robot from the previous activity, or build a completely new design.
 Mount a light sensor to the robot, point up at the lights in the room.
 If it’s a bright sunny day, you might need to pull the shades down.
 Turn off the room lights to make the robots stop moving!
Sample Code:
This program tells the rover to:
 Drive forward indefinitely, until:
 The light sensor senses the room lights have gone off
 Then stops the motors
Discussion Questions:
 What happens if you don’t explicitly tell the motors to stop?
o The car keeps on driving; computers need very detailed instructions to do what
humans want them to do. They can’t think on their own.
 How would you make the car start driving again when the lights came back on?
o Add another “Wait for Light” block, then add another “Move” block to turn the
motors back on
o You could put the program in a loop, so that it keeps going every time the lights are
turned on or off
Questions? Comments?
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8. SUNLIGHT REFLECTIONS
Goal: To use the light sensor to measure different colors/materials reflectivity. Then using this
data, predict what would happen if the earth had smaller or larger polar ice caps.
Main Themes:
 Using the light sensor to monitor ambient light
 Programming a sequence of multiple behaviors
Theory:
The white polar ice caps reflect a lot of energy back into space. If there were a smaller ice
covered area (or if the ice were a darker color), more solar energy would be absorbed by earth.
This would result in a warming of the planet.
The light sensor uses a red LED for measurement. It turns on this red LED so it reflects off of
nearby objects, helping the NXT to get a good reading.
Activity Instructions:
 The light sensor is to be used here as a measurement device. Nothing needs to be
constructed, other than plugging in the light sensor to the NXT
o Of course, if anyone is looking for a challenge, try to build an ergonomic onehanded device for measuring.
 Point the light sensor towards white paper, dark paper, the floor, a mirror, and whatever
other colors and materials you can find in the room
o You’ll probably want to decide on a “test distance” so that it’s a fair comparison
between two different materials. One inch would be a good distance to hold the
sensor away from the material.
 Keep track of the light reflection value of each material—recording data is a very
important part of science and engineering.
 Collect the objects (or materials) that have the highest and lowest values
Sample Code:
 Press the orange square on the NXT to turn it on
 Press the right arrow twice to get to the “View” option. Press the orange button to
select “View”
 Press the right arrow three times to get to the “Reflected Light” option and press the
orange button to select
 Select the port your sensor is plugged into
 You should now see the value of the light sensor
Discussion Questions:
 What was the colored material with highest value?
o The highest values are for the most luminous (lights, the sun) and the most
reflective objects (white paper, mirrors)
 What was the highest (and lowest) reading you saw? Did you get all the way to 0 or 100?
o What do you think you would need to do in order to attain those values?
 The polar ice caps are bright white snow and ice. Do you think they absorb or reflect a lot
of sunlight?
o They reflect most of the incoming sunlight back into space
 If the snow and ice were gone, what color would the north and south pole be?
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o
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Largely deep blue of ocean water. Much of Antarctica would be dark rock.
These darker colored poles would absorb much more of the sunlight, and reflect far
less back into space.
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9. ROBOTIC MUSIC
Goal: To use the NXT to generate different notes and create a musical composition.
Main Themes:
 Use of the NXT’s sound functions
 Creation of music (or at the very least, a single melody)
Theory: The NXT computer brick has a speaker on it that can produce sound at many different
frequencies. Since the speaker is very small, it doesn’t produce low notes as well at it produces
higher pitched notes.
Activity Instructions:
 Create your own song or melody
o Or try to play a well known tune (Mary had a Little Lamb, Happy Birthday, etc.)
 You can change the tone and length of the notes
 Add a loop to make your musical creation repeat
Sample Code:
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This code shows four notes being played in a loop
o You can play your melody without the loop, it just won’t repeat
In this example the first note is 100% volume, while the rest of the notes are less
than half volume
o That emphasis on the leading tone is common through much of music
Discussion Questions:
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Are you able to program multiple robots to sing at the same time?
o The tricky part is hitting the start buttons on each robot at the same time,
otherwise they’d be out of sync
 Why is the small speaker so bad at playing low frequency notes?
o The speaker is very small in comparison to the wavelength of low notes, so it has a
hard time replicating those
Questions? Comments?
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10. ROBOTIC ECOSYSTEMS AFFECTED BY POLLUTION
Goal: To explore how a robot ecosystems is affected by noise pollution.
Main Themes:
 Using a pair of robots to simulate an ecosystem
Theory: This activity is analogous to how human pollution (light, sounds, chemicals, trash)
causes problems for the natural environment. Once the pollution reaches a certain threshold the
natural rhythm (or cycle) is disrupted. Sometimes the threshold for causing disruptions is very
small.
Activity Instructions:
 Program a robot to emit a beep every 5 seconds.
 Program a second robot to listen for that beep, then emit another sound (or turn on a
light, or make a quick motor movement).
 Setting these two robots next to each other should result in a rhythmic pattern of sounds
and/or motions. Now introduce some noise pollution: have students talk or clap.
 What interrupts the robots’ pattern? How close or loud do you need to get to interrupt this
natural cycle?
 What types or frequencies of sounds most easily disrupt the robot’s rhythm?
Sample Code:
Robot 1:
Robot 2:
Discussion Questions:
 How low did you have to set the sound threshold to make the experiment work?
 Were the students in class able to be quiet enough to let the robots hear each other?
 Which robot was more affected by the noise? Why?
o Only the second robot is using a sensor, so it will be affected
Questions? Comments?
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11. ULTRASONIC MEASUREMENTS
Goal: To explore the ultrasonic distance sensor
Main
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Themes:
Animal senses: echolocation
Loops in programming
Programming math
Robotics and Biology Theory: Both robots and animals use sonar to navigate around their
immediate surroundings, often aided by other senses of sight and hearing. They emit a high
pitched “chirp” and listen for the sound waves to bounce off an object in front of them. The
longer it takes for the echo of the sound to return, the further away the object.
Bats, dolphins, and whales use sonar (a.k.a. echolocation) to detect objects in their
environment. It is believed that Dolphin’s teeth are arranged to help receive the incoming sound
and make it easier for them to pinpoint the exact location of an object. Animals can also use
echolocation for foraging or hunting for food.
Robots use ultrasonic sensors in a similar way as animals to detect the distance to objects.
Ultrasonic sensors use sound waves with a frequency above the limit of human hearing.
Activity Instructions:
 Students just need the ultrasonic distance sensor connected to the NXT
 Students walk around the room holding the ultrasonic sensor in front of them, looking
down at the readout on the NXT.
 When the value on the screen gets too small (under 50 cm? 20cm?) it probably means
you’ve gotten to a wall
o Turn the sensor to the left and right to see which direction has less obstacles
Sample Code:
 Press the orange square on the NXT to turn it on
 Press the right arrow twice to get to the “View” option. Press the orange button to
select “View”
 Press the left arrow one time to get to the “Ultrasonic cm” option and press the orange
button to select
 Select the port your sensor is plugged into
 You should now see the value from the ultrasonic distance sensor
Discussion Questions:
 Were you able to walk around the room safely, using only the readout on the NXT?
 How do animals use sonar to navigate?
 How well does sonar work for navigation in comparison to vision? What are its advantages
and disadvantages?
o Sonar can work in the dark, since it uses sound waves rather than light waves.
o Vision can work over greater distances than sonar because light generally travels
farther than sound. Sonar works well for orientation in the immediate environment
and avoiding objects close at hand.
o Soft materials absorb rather than reflect the sound and can interfere with sonar.
 How does an animal’s use of sonar compare to the robot’s ultrasonic sensor?
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o
They are very similar. Both use sound waves to measure distance to an object.
Resources:
 Interactive resource on how animals use sonar as a sense, with sample sounds from bats
and dolphins: http://www.biosonar.bris.ac.uk/
 More info on animal echolocation: http://en.wikipedia.org/wiki/Animal_echolocation
 Info on the use of underwater sonar in technology: http://en.wikipedia.org/wiki/Sonar
Questions? Comments?
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12. MEASUREMENT OF SEA LEVEL RISE
Goal: To use the ultrasonic distance sensor to measure the height of water in a sink.
Main
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Themes:
Using the ultrasonic distance senor
Measurements from satellites
Setting sensor thresholds
Theory: Measure the level of water sitting in the sink using ultrasonic distance sensor (mount
the sensor above the water and program it to sound an alarm when the water level gets within
12 inches of the sensor. If you don’t have a sink you can also use a stack of books to represent
the water level, and add a book to the stack instead of filling the sink more.) This compares to
how satellites measure sea level rise and glacier height (though they don’t use sound, they use
radio signals or lasers).
Activity Instructions:
 Students just need the ultrasonic distance sensor connected to the NXT
o You could mount the sensor so that it is pointing down into the sink
 If you don’t want to use a sink (or don’t have one handy), you can mount the distance
sensor above a stack of books or paper
o Add books to the stack to simulate the rising of the water level
 Set the ultrasonic distance sensor to sound an alarm when the water level gets within 20
cm of the sensor
 Add water (or books) to sound the alarm, then lower the level to stop the alarm
o Play with this threshold to see how sensitive it is, and how quickly the program
keeps checking the sensor value
Sample Code:
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This program waits for the ultrasonic distance sensor to get a measurement under the
threshold
Sounds an alarm (it plays a sound file of your choosing)
Loops back to the beginning of the program to keep checking the sensor measurement
Discussion Questions:

Did you drop your NXT in the water?
o It may still work. Take the battery out and let the unit dry overnight before trying
to turn it on again.
 Were you able to figure out how frequently the NXT checks the sensor value?
o It’ll be based on the length of your sound file. Try using a shorter (or longer)
sound; does that change the behavior of your robot?
Questions? Comments?
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20 of 30
13. CYCLICAL SYSTEMS
Goal: Build a cyclical system and explore its behavior. What happens when you remove any link
of the chain?
Main Themes:
 Cyclical systems
 Complicated interactions in an environment
Theory: There are a lot of examples of cyclical systems: the water cycle, chemical processes
within the human body, the food chain, etc. These systems have components that depend on
each other to create a balance and keep the cycle going continuously. If one element is removed
(or even just modified slightly), it can throw off the entire system.
Activity Instructions:
 Build the first robot to turn a motor when a student presses down a touch sensor
 Have a student hold the axle coming from the motor, and when they feel rotation, they
should put their hand in front of the distance sensor of the next robot
 Build the second robot to wait for the student’s hand to be put in front of the distance
sensor, then play a sound
 Build the third robot to hear that sound and display an image on the screen of the NXT.
 To set the cycle going, have the student press the touch sensor
o Every time the student sees the image on the NXT screen, they should press the
button again (becoming a link in the cycle)
 You can add students or robots to the cycle in order to make the best use of then number
of students
o Try making a cycle with the entire class
Sample Code:
Robot 1:
Robot 2:
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Robot 3:
Discussion Questions:
 Were you able to remove one of the links in the chain without having the cycle stop?
 How many seconds did it take for 1 complete cycle?
o What was the fastest individual component?
o Which was slowest?
Questions? Comments?
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14. WIND POWER
Goal: Final multi-period project: Build a wind turbine and hold a contest to see which wind
turbine is the most efficient.
Depending on the number of class periods available, you can build something for the wind
turbine to power: a merry go round, a series of lights, a motorized drawbridge. Have a student
vote to name the favorite interesting contraptions the wind turbines power.
Main Themes:
 Wind power
 Efficiency of turbine blades
Theory: A turbine is a machine used for capturing energy from a flowing fluid. A wind turbine
extracts energy from the blowing wind. Coal and nuclear power plants extract energy from super
heated steam (the steam had been created by either coal or nuclear material), and hydroelectric
power plants have a turbine that extracts energy from flowing water. A turbine could be thought
of as the opposite of a propeller or fan—the turbine uses flowing fluid to rotate the blades while
the fan uses rotating blades to create a flowing fluid.
It’s worth noting that a windmill is a wind-powered mill for grinding grain while a wind turbine
generates electricity.
Activity Instructions:
 You’ll need to get an electric fan to provide some wind for the students’ wind turbines.
 Use the NXT to display the number of motor rotation degrees on the screen.
 Blade construction and design is an important aspect of this challenge.
o You make blades out of cardboard, LEGOs™, aluminum foil, plastic wrap, fabric,
wood, etc
 Set up each windmill in the wind and give it 60 seconds to see how many times the blades
rotate.
o The more rotations, the more efficient the blade design is. (This assumes that each
windmill is exposed to the same wind conditions, so place objects accurately when
testing them.)
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Construction Tips:
 Here’s a picture of a wind turbine that uses the NXT as a stable base: (the blades are
made out of paper and are taped to the LEGO™ pieces)
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Here’s a close up of the motor and gearing: (You may have to add gearing if the blades
have trouble turning)
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If you need to include gearing, here’s a step by step assembly guide for the design shown
here. Collect these parts:
Close-up of axle with worm gear and spacers
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Step 2:
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Step 3:
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Step 4:
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Step 5:
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Step 6:
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Step 7:
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Step 8:
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Step 9:
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Step 10:
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Step 11:
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Step 12: Place the biggest gear on the axle coming out of the motor. Check to make sure
the black worm gear and the big gray gear mesh smoothly. You should be able to turn the
worm gear axle and make the big gear slowly rotate.
Sample Code:
 Press the orange square on the NXT to turn it on
 Press the right arrow twice to get to the “View” option. Press the orange button to
select “View”
 Press the left arrow 4 times to get to the “Motor degrees” option and press the orange
button to select
 Select the port your motor is plugged into
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You should now see the number of degrees displayed on the screen (it will say “360”
or “-360” depending which direction you turn the motor)
Discussion Questions:
 Did you notice any patterns in which wind turbines did well?
 How many blades did you use in your design? What shape are they?
 Look on the internet for other wind turbines—how many blades to they have? What shape
are they?
 If you put your wind turbine in the center of the fan’s “wind column” (where the strongest
wind is) versus out on the edge of the wind column (where it is slower), do you expect to
get more rotations in 60 seconds? Or less?
o There are cases where you’ll get more rotations with a slower wind speed. It would
mean that the wind turbine is optimized for that slower speed. Also, the strongest
wind may break some blades—in which case you’d certainly expect to see less
rotations!
Questions? Comments?
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