If you are grading "Toan Kumon Pdf" at home, do not simply say "wrong." Kumon requires students to redo the problem until it is correct. This builds persistence.
If you cannot find high-quality or legal Kumon PDFs, do not worry. There are excellent Vietnamese and international alternatives: Toan Kumon Pdf
Website: khanacademy.org (available in Vietnamese). Khan Academy covers everything Kumon does (addition to calculus) but includes and automatically generated questions. It is completely free and legal. While it lacks the "PDF" printout, you can screenshot problems. If you are grading "Toan Kumon Pdf" at