Skip to main content

Speed Stacker

Working in pairs, create an algorithm (step-by-step instructions) to achieve a simple task – in this case, stacking cups.

Back to Activity Finder


  • What supplies will you need for this activity?  
  • Is there anything that you will need to print out for this activity? 
  • How will you make your pairs? How will you decide who will be the robot and who will be the programmer? 


  • Work in pairs and assign one person to be the programmer and one to be the robot.  

Programmer Instructions: 

  • Choose a cup stack sheet (don’t let the robot see!) 
  • Use the symbols from the symbol key to write instructions for the robot to follow in order to build your chosen cup tower. 
  • Give the robot your instructions. 
  • After the robot has finished, debug your code (catch any problems and try to solve them). Write new instructions and try again, if needed. 

Robot Instructions: 

  • Take the cups and practice stacking them away from the programmer. 
  • When the programmer calls you over, use their instructions to build a tower. Use the symbol key to decode their step-by-step instructions.  
  • When you are finished, check to see if the tower looks the same as the Cup Tower sheet. If it does not, work with the programmer to fix the instructions. 
  • Try again! Keep debugging until the instructions are correct. 


  • Once your robot has built the tower, switch roles and try again! 


  • Was it hard to write a program for the robot? 
  • As the robot, was it hard to follow the program? 
  • What would make writing and following the program easier in the future? 
  • Can you apply anything you learned here to real life? 
  • Remember to submit your activities on our Scouts for Sustainability Take Action Map


  • Plastic cups (10 per pair) 
  • Paper and pencils 
  • Printed symbol key and cup stack sheets (the cup stack sheets should be cut up ahead of starting the activity).  

Keep it Simple

Work in teams of three – have two people write the code together (the programmers) and one person follow it. Two heads are better than one and might make it easier to create your code!  

Take it Further

Make it into a competition! Have pairs sit back-to-back with the programmers all facing towards the Scouters. Show all the programmers the same tower at once and have them race to write down an algorithm for their partner to build. When they are finished, they can pass their written algorithm to their robot partner. Robots with an algorithm can start building their tower. Programmers may watch and take away the paper at any time to “debug” and adjust their code before returning it to their robot. Whoever successfully builds their tower first wins!