External Graders - Xqueue#


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As an online course designer, it is essential to understand and utilize the various tools at your disposal to create effective and engaging learning experiences. One such tool is the external grader, or Xqueue, within the Open edX platform.

The platform employs external graders or xqueue to assess student submissions for specific problems. These fundamental grading engines separate from the main edX platform and can independently evaluate students’ responses based on predefined criteria.

External graders offer a flexible solution for assessing complex assignments that Open edX’s built-in assessment tools cannot automatically grade. This includes projects like essays or coding tasks where answers vary greatly and require more nuanced evaluation.

How External Graders Work in Open EdX#

To understand how external graders work, consider them a separate service communicating with the platform through messages. When a student submits an answer to a problem set to be graded externally, Open edX sends a message to the external grader through xqueue containing the student’s response.

The external grader then evaluates the response based on predefined criteria and sends a grading message via xqueue. This grading message contains the score and feedback the student will receive on their dashboard.

It is worth noting that external graders are typically designed and managed by course staff or third-party services. As such, the team can customize the grader to fit specific grading requirements for different assignments.

The Role of Xqueue in Open EdX#

The primary role of xqueue is facilitating communication between the main platform and external graders. It is a messaging queue system that delivers grading tasks from Open edX to external graders and returns grading results to the platform.

In addition to this core function, xqueue also provides features that enhance the flexibility and reliability of the grading process. For instance, it allows for asynchronous grading, meaning that grading tasks can be processed in no order and at separate times. This is particularly useful for assignments that take a long time to grade.

Moreover, xqueue supports retrying failed grading tasks and logging grading activities, which helps ensure that all student submissions are adequately assessed and provides valuable data for troubleshooting and improving the grading process.

There are several advantages of using xqueue in online course design:

  • Flexibility: Xqueue enables you to use custom grading engines that can oversee diverse assignment types beyond what is supported by Open edX’s built-in assessment tools.

  • Scalability: With xqueue, you can simultaneously utilize multiple external graders to manage numerous student submissions, improving grading efficiency.

  • Reliability: Xqueue’s features, like asynchronous grading, retrying failed tasks, and logging activities, enhance the reliability of the grading process.

  • Feedback Quality: External graders can provide more detailed and personalized feedback than automated grading tools, helping students learn more effectively.

See also

For further reading and learning about xqueue, visit Open edX’s documentation about it.