My gumball machine coins disappeared… and in their place was a secret message.

The only way to crack it? Build an Enigma-style cipher machine using LEGO SPIKE Prime.

In this challenge, we design and program a LEGO robot that can encode and decode messages using a Caesar Cipher. One motor selects the cipher key, another selects letters, and the SPIKE hub displays everything as the code comes to life.

Along the way, we:

• Build a working cipher machine with LEGO SPIKE Prime
• Use motors as input dials for letters and cipher keys
• Create an alphabet list (array) to store letters
• Apply a shift to encode and decode messages
• Troubleshoot edge cases at the start and end of the alphabet

Once the code is cracked, the mystery is solved… and the gumball machine is back in business 🍬

This project is perfect for:

• Computer science fundamentals
• Cryptography for kids
• FIRST LEGO League teams
• LEGO robotics classrooms

Want to try this challenge yourself? Grab your SPIKE Prime kit and start decoding!

Here is my code to get you going!

Classroom Challenge: LEGO Enigma Machine

Challenge Story

The coins for the gumball machine are missing! In their place is a secret coded message. Your mission is to design and program a LEGO SPIKE Prime Enigma-style machine that can encode and decode messages using a Caesar Cipher. Crack the code, recover the coins, and save the day.

Learning Goals

• Understand how a Caesar Cipher works
• Use lists (arrays) to store and access data
• Apply shifts to encode and decode letters
• Use motors and buttons as inputs
• Debug edge cases at the start and end of the alphabet

Materials

• LEGO SPIKE Prime Hub
• 2 Motors
• Building pieces for dials/buttons
• Computer or tablet with SPIKE app

Build Requirements

Your Enigma Machine must include:

• 🔄 Motor 1: Select the cipher key (shift value)
• 🔤 Motor 2: Select a letter
• ◀️ Left Button: Decode a letter
• ▶️ Right Button: Encode a letter
• 📟 Hub Display: Show the selected letter and result

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💻 Programming Tasks

1. Create a list (array) that holds the alphabet (A–Z)
2. Program Motor 1 to select a cipher key
3. Program Motor 2 to select a letter from the list
4. Encode the letter by shifting forward
5. Decode the letter by shifting backward
6. Fix errors when shifting past A or Z

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🧠 Think About It

• What happens if your shift goes past Z?
• How can you loop back to the start of the alphabet?
• How would this cipher change if we added symbols or numbers?

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🧪 Bonus Challenges (Optional)

⭐ Add sound or light feedback when a letter is encoded

⭐ Decode a full word instead of a single letter

⭐ Hide the message somewhere in the room for another team

⭐ Increase difficulty with a random cipher key

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🏁 Success Criteria

✅ Machine encodes and decodes letters correctly

✅ Cipher key can be changed using a motor

✅ Alphabet list is used in the program

✅ Edge cases (A/Z) work correctly

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🏆 Mission Complete!

You cracked the code, found the coins, and unlocked the gumball machine. Great work, codebreaker!

Activate Mars Communications Challenge

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🧭 Mission Brief

You’re designing and programming a LEGO Spike Prime rover to navigate across a Martian landscape, activate an underground communications satellite, and send a “signal” back to Earth—just like real Mars rovers supporting human exploration.

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🎯 Challenge Instructions

Phase 1: The Challenge

• Objective: Drive your rover from base, push the hidden activation button in the ground, deploy the satellite, and broadcast the signal.
• Rules: Start inside base. No touching robot outside base. Mission success when rover triggers satellite and returns.
• BUILD: Build the satellite mission model with directions in the YouTube video.

Phase 2: Brainstorm & Sketch

• Draw a rough prototype: What sensors will you need? How will you push the satellite activation? How will you detect and line up with the button?

Phase 3: Complete the Challenge

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Deep Space Communication

Satellite dishes are a type of antenna that uses radio waves to receive or transmit data. On a human mission to Mars, they’d be used to transmit messages between Earth and Mars. Radio waves travel at the speed of light, and because the distance between Earth and Mars is variable, there’s an approximate delay of between four and twenty-four minutes in communication between the planets.

NASA’s Deep Space Network (DSN)

NASA operates a global system of giant antennas called the Deep Space Network. These are located in:

• California (Goldstone)
• Spain (Madrid)
• Australia (Canberra)

They’re spaced around the Earth to allow constant communication with distant spacecraft. The dishes are huge—up to 70 meters wide—so they can catch the tiny signals sent from across the solar system.

Delay in Space Communication

Because radio waves travel at the speed of light, there’s a delay when sending or receiving signals from space.

• A message from Earth to Mars can take anywhere from 4 to 24 minutes one way.
• Voyager 1, the farthest human-made object, takes over 21 hours to send a signal back!

This is why real-time conversations with astronauts on Mars would be impossible.

Laser Communication Is the Future

NASA is testing laser-based communication, which can send more data much faster than traditional radio waves.

• It’s called Deep Space Optical Communication.
• In 2024, a laser from the Psyche spacecraft sent data over 140 million miles at speeds up to 25 megabits per second!

This could be the key to streaming high-quality video from the Moon or Mars one day.

What the Deep Space Network Does

The DSN does more than just listen. It:

• Sends commands to spacecraft
• Tracks their speed and location
• Receives science data
• Helps navigate through space

Without the DSN, we’d lose contact with most space missions!

Why Three Locations?

Each DSN station is 120 degrees apart around the Earth so that at least one of them always has a view of a spacecraft, even as the Earth rotates. This setup allows 24/7 communication with distant probes.

Satellites Closer to Earth Use a Different System

Satellites that orbit Earth don’t use the Deep Space Network. They use a different group of ground stations called the Near Earth Network. These satellites help with weather forecasting, GPS, and communications here on Earth.

The SCaN Program

NASA's Space Communications and Navigation program (SCaN) manages all the networks—both for deep space and near Earth. They’re responsible for upgrading antennas, developing new technology like lasers, and preparing for future Moon and Mars missions.

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💡 Build & Code Hints

Area	Hint
Drive Base	Use a sturdy wheel base that can travel straight and align easily.
Activation Arm	A lightweight beam or fork that can push just enough—not too much—to trigger the activation mechanism.
Sensors	Use Ultrasonic to detect when you’re close to the button; use Color Sensor or distance tracking to keep your path straight.
Programming	Use loops for straight motion, conditional waits to stop at precise points, and fine motor power settings for controlled pushes.

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📐 Step-by-Step Measurements & Angle Calculation

Step 1: Measure distance from base to satellite button in your setup (e.g. 40 cm).

Step 2: Calculate turning angles if you need to approach the button from the side:

• If the approach path veers, use geometry/pacing to compute heading angles.

Step 3: Sample Code

Encourage students to fill in their exact measurements and calculated angles.

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📺 Final Video Solution

Once students have built and programmed their rovers, they can watch the final completed mission. The video demonstrates a working solution—from navigation to block alignment to satellite activation and return to base.

“Mission Walkthrough” — Compare your approach with our at-home version

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✅ Evaluation & Reflection

Self-Assessment:

• Did your robot trigger the satellite reliably?
• Was your code precise and consistent?
• Did you work collaboratively and solve issues creatively?

Badge Levels:

• Bronze: Activation attempt but fails
• Silver: Satellite deploys but unstable
• Gold: Satellite upright and stable
• Platinum: Adds extra features beyond requirements

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🧰 Lesson Resources

• Printable measurement & pseudocode worksheet
• Extension ideas: vary button placement, sensor combos, timing constraints

🚀 Your Challenge:

Can you build a LEGO robot that acts like a real flower?
Your robot should spin slowly to look for light, then stop when it finds the sun (or anything yellow)!

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🌱 What Do Real Flowers Do?

Have you ever noticed how sunflowers turn to face the sun? That’s not just for fun—it’s a real plant behavior called phototropism.

🌞 Phototropism means:

Plants grow or move in response to light.

• 🌻 Sunflowers face east in the morning and follow the sun during the day.
• 🌿 The top of the plant grows faster on the shady side, which makes it bend toward light.
• 💡 Plants need light to make food through a process called photosynthesis.

💬 Fun Fact:

Some flowers stop turning once they’re grown, but younger ones still move every day!

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🔧 Robot Build Instructions

You’ll build a flower that:

• Spins using a motor
• Looks like a flower using bricks and petals
• Stops when the color sensor sees yellow or a bright light

🛠️ Step 1: Build the Spinning Base

Build a sturdy base and mount a motor horizontally so it can spin a platform.
Make sure the whole thing doesn’t tip over when spinning!

We used the Twirling Teacups lesson as an introduction to a spinning base.

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🪴 Step 2: Make the Stem

Use LEGO beams to make a vertical stem that connects your flower head to the spinning platform.

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🌸 Step 3: Create the Flower

Your color sensor becomes the center of the flower.
Decorate it with bright petals—but make sure it can still “see” colors in front of it!

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💻 Coding the Robot

Use this basic idea for your code:

forever:
   Spin slowly
   If color sensor sees yellow or a bright light:
       Stop spinning

📹 Watch the example video for how this works:
Watch on YouTube

💡 Tip: You can use "wait until color sensor sees yellow" in your program, or detect brightness using the reflected light sensor mode.

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🧪 Test Your Robot

Try these tests:

• Shine a flashlight near the sensor. Does it stop?
• Place a yellow object in front of it. Does it freeze?
• Does it keep spinning if there’s no light or yellow?
• Can you make it spin again after it stops?

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🎨 Bonus Challenges

• Decorate your flower with more petals, leaves, or a bug friend!
• Make it change colors using lights when it stops.
• Build a garden of robots and see how they all behave together!

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📓 Record Your Learning

Use these questions in your science notebook:

Question	Your Answer
What is phototropism?
How does your robot behave like a real flower?
What does the sensor do in your robot?
What did you change during testing?
What would you do differently next time?

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🌼 Share Your Build!

Take a photo or video of your robot in action and share it with your class or post with permission!

Mission Brief

You're an astronaut-robotics engineer stationed on Mars Base 7. A massive dust storm has just passed, revealing delicate ice crystals on the red surface. These crystals may hold the key to:

• Evidence of past or present life
• Essential water resources for future habitats
• Fuel production and oxygen for return missions

But there's a problem: the crystals are too fragile to be picked up by normal grabbers. Your mission is to design a rover with a One‑Way Curtain to collect them safely and bring them home.

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🎥 Watch the Mission Video

Check out the full mission walkthrough:
https://youtu.be/20_-gqwPFDc

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Step 1: Build the One‑Way Curtain

Create a mechanism that lets ice shards pass into the collection basket—but won’t let them fall out.

• Use LEGO beams or Axel elements as flaps
• They should hang from a Pivot Point
• Attach a STOP bar to prevent the flaps from opening the wrong way.
• Mount it at the front of your rover
• Test: make sure objects slide in—but not back out

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Step 2: Build Your Rover

Start with a simple SPIKE Prime drive base:

• 2-motor driving chassis (wheels or treads)
• One‑Way Curtain in front
• Collection area big enough for multiple shards

Add sensors, color tiles, or bumpers if you like!

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Step 3: Program the Mission

Using SPIKE Prime’s coding interface:

1. Drive forward to sweep crystals
2. Turn and repeat to cover the area
3. Return to the Home Base when done

Tip: Use loop blocks, timers, or sensor-based navigation to make it reliable.

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Step 4: Create Ice Shards

Make your own LEGO “ice crystals”:

• Translucent 1×1 round tiles or slopes
• Light-blue or clear studs
• Vary shapes and sizes for more fun

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Your Challenge

Build, attach, code, and collect:

MISSION GOALS

• Design a rover with a One‑Way Curtain
• Collect at least 5 ice shards
• Return to Home Base

Document your mission: take photos or videos!

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🗣️ Share & Compete

Once your mission is complete, do this:

1. Comment below the video with your rover’s design and strategy
2. Like the video if you enjoyed the challenge
3. Subscribe for more robotics missions
4. Tag us on social media with your rover—your build might be featured!

A LEGO Spike Prime Challenge to Save the Mars Base

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🚀 Your Mission

The Mars base has lost power. The lights are out. Systems are offline. The only way to reach the life support core is through a maze of narrow vents.
Your job is to build and program a LEGO Spike Prime robot — codenamed VENT Bot — to navigate the maze and save the crew.

Download your printable mission materials:
👉 VENT Bot Mission Tracks Printables (PDF)

💡 Pseudocode Mission Log (PDF)

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🧱 What to Build

Begin by laying out a maze with items from home, class, or the printable maze tiles.

Your robot must be compact and precise. Use your LEGO Spike Prime kit to build a robot that can:

• Fit in a narrow maze
• Drive forward in straight lines
• Turn accurately using the internal gyro sensor
• (Optional) Use color or distance sensors to detect obstacles

Required components:

• 2 drive motors (left + right)
• Spike hub (with built-in gyro)
• Small chassis build with wheels
• Wires routed neatly so they don’t get caught in the maze

HINT!

We used the Driving Base 1 building instructions from Competition Ready.

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💻 What to Code

You’ll need to:

• Measure the length of each maze segment (in centimeters)
• Record the angle of each turn using the robot’s yaw angle sensor
• Plan your program with pseudocode
• Write your code in the Spike app using movement and turn blocks

Example pseudocode:

Move forward 40 cm  
Turn right 90°  
Move forward 20 cm  
Turn left 45°  

Use the printable Maze Mapping Log to record each step!

HINT!

Watch this video about using the Gyro Sensor to make precise turns.

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📏 Step-by-Step Instructions

1. Set up your maze using tape, tiles, or printed paths.
2. Test your robot: Can it move straight and turn consistently?
3. Use a ruler or tape measure to record distances between turns.
4. Use the gyro sensor to test turn angles (e.g., 90°, 45°).
5. Record your pseudocode for the entire maze path.
6. Translate your plan into a working program in the Spike app.
7. Test and revise — update your code until the robot can complete the maze!

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🎯 Success Criteria

• Robot completes the maze without hitting walls
• Distances and turns are accurate
• Code is organized and based on measured data
• You used your pseudocode as a planning tool

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🎥 Watch the Full Mission Video

See how the mission begins, how the robot is built and programmed, and how VENT Bot saves the Mars base! Leave us a comment on YouTube if you completed the mission!