Purdue’s Charlie AI transforms learning by empowering student writers

What if students could get in-depth, timely feedback about their writing before submitting it for a grade? What if that feedback was customized to an instructor’s rubric for that specific assignment? Meet Charlie, an AI-powered writing assistant developed by Purdue’s instructional technology team and embedded within the Circuit peer-review platform. 

“One of the big concerns about peer review has always been the accuracy of the reviewers,” said Jason Dufair, lead application developer. “So what Circuit brought to the table was a way to calibrate each of the students, who are also the reviewers in later phases of the assignment, against a set of known assignments that the instructor has already graded.”

Designed by Purdue developers to fill gaps in the instructional technology market and provide a robust peer-review system, Circuit launched around 2015. Over time, it evolved into a more flexible assignment tool that instructors could customize to fit their course needs with additional self-review and instructor-review options. However, the development of Charlie marked a significant milestone in this evolution, addressing the growing demand for actionable, timely writing feedback.

Lindsay Hamm, assistant teaching professor in sociology, has played a key role as a subject matter expert since Charlie’s development began in 2019. Initially Charlie offered simple point estimates for essays, but it has since evolved to deliver detailed, constructive comments tailored to each section of an assignment’s rubric. This allows students to pinpoint areas for improvement and revise their work before final submission. 

As Dufair noted, an important distinction is that Charlie doesn’t grade the students’ work. Rather, it is a tool to help identify areas where students can strengthen their arguments and better address rubric criteria before submitting their assignments for a grade.

Early iterations of Charlie could predict a student’s score but did nothing to help students improve their writing. Developers worked with the Purdue Online Writing Lab and instructors like Hamm to train Charlie to provide more qualitative, actionable feedback. Charlie provides general guidance but will never advise students on specific words to change or actions to take. This approach reduces student anxiety and mirrors the kind of feedback they might receive in office hours or in the writing lab.

“One thing to keep in mind is that no matter how great the writing is, Charlie will always provide feedback and areas for improvement,” said Casey Wright, lead application developer. “We try to warn students about that.”

The quality of the rubric for an assignment is key to the efficacy of Charlie’s feedback. Hamm worked with the instructional technology team to develop built-in rubric templates, making it easier for instructors to adapt Charlie to their specific courses. 

With Circuit’s Brightspace integration and the recent ability to create submission-only assignments where students can opt to receive Charlie’s feedback, the team has worked to drastically lower the barrier to entry for course adoption, Wright remarked. 

What sets Charlie apart from other AI tools?

Just like a home toolbox features an array of tools for specific projects, there are different AI tools for various tasks, and each one has value. For example, some AI tools are used to generate novel hypotheses or for ideation and general writing guidance, whereas Charlie’s feedback is specific to a particular course or instructor.

Supported by the University Innovation Alliance, Purdue’s approach stands out for its emphasis on rubric-driven, constructive feedback rather than generic writing advice. Hamm notes that Charlie not only boosts students’ confidence in writing but also improves their ability to give and receive peer feedback, fostering richer academic dialogue and collaboration.

“Now a student can come in and say, ‘Charlie keeps saying my counterargument isn’t very strong’ or ‘Charlie says my thesis statement could be narrower.’ Then I can really home in on what they need to work on for those higher order issues,” Hamm said. “My hope for AI — and I know it’s an optimistic hope — is that it can break down more barriers and help people talk to each other more confidently as they have more access to information.”

Charlie’s success in sociology has sparked interest from other departments, including pharmacy and graduate governance courses.

From a cybersecurity standpoint, submitting information to Charlie is as secure as any other information sharing within the Purdue digital ecosystem. Privacy and data security are top priorities when handling student data, and all submissions comply with Family Educational Rights and Privacy Act standards. In addition, engagement with Charlie is optional. 

Charlie exemplifies Purdue’s dedication to leveraging technology for student success, offering a scalable, supportive and effective tool for writing improvement across campus.

Getting started with Circuit’s Charlie

Faculty interested in using Circuit can log in at peercircuit.org, link their courses to Brightspace and set up assignments with just a few clicks. Comprehensive help resources and direct support are available at tlt@purdue.edu. Additionally, instructors can access in-depth demonstrations and resources from a fall 2025 session titled “Open Kitchen: Exploring AI Tools Together,” provided as part of the AI Bytes workshop series.