Chain Reaction Challenge
Introduction
A Rube Goldberg machine is a complex chain reaction designed to complete a simple task in the most over-the-top way possible! Think dominoes, marbles, ramps, pulleys, wind-up toys, and random household objects working together to make something happen—like flipping a light switch or dropping a ball into a cup.
This activity is a fun way to explore engineering, physics, and creativity, encouraging Scouts to design, build, and test their own contraptions.
What you'll need
- Household objects like books, cups, spoons, dominoes, marbles, string, pegs
- Tubes, ramps, toy cars, balls, balloons
- Dominoes or Jenga blocks
- Tape, scissors, glue, blu-tack
- Paper and pencils (for sketching the design)
- A flat surface or a table to build on
Before you begin
-
Discuss with the Unit:
- What everyday tasks could be overcomplicated in a fun way? (E.g. turning on a light, ringing a bell, pouring cereal.)
- How do forces like gravity, momentum, friction, and energy transfer make machines work?
- What materials would be useful for a chain reaction?
-
Decide on the challenge:
- Will this be an individual or Patrol competition?
- Will there be judging criteria (e.g. longest chain reaction, most creative, funniest)?
- Does the machine need to achieve a specific goal at the end?
-
Do a Safety Check:
- Ensure the design is safe and stable—no heavy objects that could fall dangerously
- Avoid fragile or breakable items unless properly secured
See Rube-Goldberg machines in action
Activity
-
Plan Your Machine:
- Decide what your machine will do (e.g. pop a balloon, knock over a cup, push a button)
- Sketch a blueprint of your idea
- Choose materials that will work well together
-
Start Building:
- Begin with one section at a time, testing each piece before adding the next
- Think about how the energy will transfer between objects (e.g. rolling, swinging, knocking over)
- Use trial and error—adjust if something doesn’t work
-
Test and Refine:
- Keep testing parts of the machine to see if they work smoothly
- If something fails, figure out what went wrong and improve it
-
Final Run and Film It:
- Once it works, record a video or demonstrate it to the Unit live
- Count how many steps it takes to complete the task
Change the challenge level
Easier:
- Use a simple task with only a few steps
- Work in pairs instead of individually
- Provide a set list of materials to simplify decision-making
Harder:
- Add a minimum step requirement (e.g. must have at least 7 chain reactions)
- Introduce a time limit to build and test
- Have teams compete for the most creative, longest, or funniest machine
- Try making a machine that resets itself after each use
Reflection
- What was the most fun part of the challenge?
- What did you learn about forces and energy transfer?
- What was the biggest problem-solving moment, and how did you fix it?
- If you did it again, what would you change or improve?
- How do engineers and inventors use similar processes in real-world designs?