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Implementing VEX 123 STEM Labs

STEM Labs are designed to be the online teacher’s manual for VEX 123. Like a printed teacher’s manual, the teacher-facing content of the STEM Labs provides all of the resources, materials, and information needed to be able to plan, teach, and assess with VEX 123. The Lab Image Slideshows are the student-facing companion to this material. For more detailed information about how to implement a STEM Lab in your classroom, see the Implementing VEX 123 STEM Labs article.

Goals and Standards


Students will apply

  • How to use a debugging process to identify, find and fix bugs in a project with the 123 Robot.

Students will make meaning of

  • How the 123 Robot will sometimes not behave as expected due to a bug in the code, which can be fixed by applying a debugging process
  • How debugging is an expected part of coding and a learning opportunity

Students will be skilled at

  • Pushing to wake the 123 Robot
  • Connecting the Coder to the 123 Robot
  • Matching each behavior of the 123 Robot to a specific Coder card
  • Identifying, finding and fixing bugs in a project
  • Using the Step button on the Coder to identify bugs in a project

Students will know

  • How to identify, find and fix bugs in projects
  • That the debugging process includes identifying, finding, and fixing bugs



  1. Students will identify that a bug occurs when the 123 robot does not behave as expected, and that the steps of the debugging process are identify, find, and fix.
  2. Students will apply the debugging process to identify, find and fix a bug in a project with the 123 Robot.


  1. In Engage, students will view a project with a bug in it, and discuss what a bug is. In Play Part 1, they will work as a class to identify the bug, find the specific Coder card where the bug occurs, and fix the bug. They will view the project a second time, without the bug, and describe the steps of the debugging process as identify, find and fix.
  2. In Play Part 2, students will be given a project (using the Coder) that contains a bug. They will work in small groups to use the debugging process to identify what the problem is in the project and locate the Coder card that is causing the bug. They will then choose a Coder card or cards to fix the bug, and run the project to test it. 


  1. During the Mid-Play Break, students will share and discuss other times they have encountered bugs in their coding projects and will share how they would now apply the debugging process to fix those bugs.
  2. During the Share section, students will share how they used the debugging process to find and fix the bug in their project.

Connections to Standards