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Pros: It's trained to help with specific subject areas and goes beyond the basics.
Cons: Given its limited free version and technical writing focus, it might have limited use in the K–12 classroom.
Bottom Line: Solid tool with free tier, but mileage on usefulness will vary.
How Can I Teach with This Tool?
Similar to some other available tools, Trinka offers support for writers trying to improve grammar and style and also offers a plagiarism checker. For students who struggle with writing conventions, tools like Trinka can help build a better understanding of some fundamental skills. For others, building in time for editing, revision, and the good old-fashioned writing process might be a better option. It's likely to be something teachers suggest as an option to students rather than a tool to deploy to a whole class.
Trinka makes a point of being a tool for academic and technical writing, perhaps limiting its appeal in most classrooms. It is, however, useful for students trying to improve the quality of their writing. The free account offers users up to 10,000 words and one plagiarism check per month -- probably enough for most middle and high school students -- with the option to upload documents or to install browser extensions (for Chrome, Firefox, and Edge). Users can also connect OneDrive, Dropbox, and Google Drive accounts to Trinka. Depending on privacy rules in schools, the option to upload individual documents is likely the most useful for teachers and students.