Work samples can be included in Comprehensive Records. I included some writing samples within the body of my course descriptions. I tried to choose things that were not too long, perhaps something that had won an award (published, or got an "A" grade from someone else). And I tried to get some variety: perhaps a short story and a piece of research.
Other than a writing sample, I would just be prepared to give a sample of something they might ask you for. We were asked for a science lab report, a graded English paper, and math in my son's handwriting. It's hard to know exactly what your college will ask you for, so be prepared to give a sample in any class on your transcript.
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