Years ago only a handful of educators did not mark with the bright, bold color of red when marking students work from primary to post secondary. Red was the color of choice because it identified the errors, how could anyone miss the brightness of the color smeared across their work.
Today, more and more educators are opting for the softer colors of blues, greens, and purples to correct student work because they believe it does less psychological harm to the student. I am one of those educators, the color of the pen has an impact on the students self esteem. A child who sees his/her paper with red markings is less likely to examine the errors and to correct them for the next test or assignment. The red markings makes the students retreat not become motivated to have less red markings next time. Students are sensitive and they do not want to be labeled as the "dumb" kid in class but if they are continually receiving papers sprayed with red markings, the others student will label him/her without knowing the marks.
Should I use a Red Pen to Grade Papers? Learn the pros and cons.