When students are ready to complete the Explore performance task for AP scoring purposes, they should not collaborate on any portion of this performance task.
When students are ready to complete the Create performance task for AP scoring purposes, they can collaborate, as long as each student develops and contributes his or her own independently developed algorithm and abstraction. The code should be labeled based on what was developed together and what was contributed by each partner. This can be done through the use of program comments.
However, students cannot collaborate on the written response or video for the Create performance task. The video of the program must be developed independently. The written responses must be written independently, and responses to parts 2C and 2D should be centered around the algorithm and abstraction the student developed independent from their partner. Additionally, the response to part 2B should focus on at least one of the difficulties or opportunities in something they did independently; the other can be either independent or collaborative.
The AP Computer Science Principles Course and Exam Description (.pdf/2.05MB) provides teachers with examples of acceptable ways for students to collaborate while completing the Create performance task.