When practicing for the ACT, toss the eraser, instead, cross out your mistakes, thereby keeping them visible. Learn from them so that you do not repeat them. In my ACT prep class, I provide a form for students who are practicing for the ACT. By using this form they can continually evaluate their work. It is a learning tool which magnifies errors in order to separate them from accurate answers. Mistakes are a great teaching tool. Erasing them takes the memory of the problem with it. Unless you are working on the FINAL draft of a paper, inaccuracies will remind you what not to do and how you arrived at what to do.