Speed Stacker

This activity reinforces basic computational thinking through using code to build cup towers. Learners will work in pairs as ‘robots’ and ‘programmers’ to write out algorithms, or step-by-step instructions, for each other, then debug and problem-solve their code together.

This activity was created by Thinkersmith for Hour of Code

Materials:

• Plastic cups (10 per pair)
• Paper and pencils

Before the lesson...

• Review key coding concepts and ensure you are confident describing them to your group
• Print the Symbol Key and Cup Stack sheets for the main activity (1 per table)
• Cut out cup sheets ahead of time

Run through this example as a class.

Pair up learners. One person will begin as the programmer, and one as the robot.

Programmer instructions:

1. Choose a Cup Stack sheet from the pile (don’t show the robot!)
2. Use the symbols from the Symbol Key to write instructions for the robot to follow, in order to build this cup tower
3. Give the robot your instructions
4. 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:

1. Take the cups and practice stacking them away from the programmer
2. When the programmer calls you over, use their instructions to build a tower. Use the Symbol Key to decode their step-by-step instructions.
3. 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.
4. Try again! Keep debugging until the instructions are correct.

After running through once, learners will switch roles with their partners.

Learning Outcomes

We created and decoded algorithms (our cup stacking instructions).
We learned the importance of sequences and clear instructions in coding.
We worked with our partners to debug (or fix) our instructions.
We practicing modularizing by breaking down a larger task into smaller parts.

Assessment Ideas

Have pairs submit their final instructions with a written reflection outlining their debugging process.

Make it into a competition!

1. Have pairs sit back-to-back, with the programmers facing you and the robots looking away (no peeking towards the front!)
2. Show all programmers the same tower at once and have them race to write down an algorithm for their partner to build
3. When they are finished, then can pass their written algorithm to their robot partner (robots must still face away - no peeking!)
4. Robots with an algorithm can begin building their cup tower. Programmers may watch and take away the paper at any time to “debug” and adjust their code before returning it to their robot.
5. Whichever pair successfully builds the tower first, wins!

Original Lesson by Thinkersmith

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