Ideal student writes ideal paper, thus providing indicator of understanding. Results are described honestly, briefly, and vividly. And so on, including correct format, references, mechanics, and grammar. Professor C might record the grades shown in the third table. Assessment via PTA 1.
Scientific paper is a visible representation of scientific understanding.
Same as for grades. Students write papers in scientific report format. Ideal student writes ideal paper, thus providing indicator of understanding. Same as for grades. Professor consciously notes non-uniform student performances regardless of grade.