Black or blue. When primary schools require pens, it is generally required to use black or blue pens. Because black and blue have very high color rendering, they can see themselves more clearly and are more convenient for teachers to review, so Dongsheng Road Primary School uses blue or black pens. Generally, pens will be used in the second to third grades of primary schools, and ordinary primary schools will also offer corresponding hard pen calligraphy courses to help students correct their handwriting.