First, I thought about how a student with a memory problem might work with a ruler and measurments. It might be difficult for them to retain a mesurement in their working memory long enough to complete a task with it. An easy solution I thought might be to have the student simply use a dry erase marker to mark the measurment on the ruler until he or she has had time to work with it or record it elsewhere. The mark can then quickly and easily be erased.