The keyboard strokes that become digital displays that humans recognize as words and sentences are actually a series of digital signals. Those signals are stored as magnetic signals or optical signals on disks or electrically in memory. As long as the physical media are safe and the file is not otherwise compromised, the messages can be saved with precision indefinitely. If an appropriate system to read the files is available, the file can be recreated as well. It is not unusual for computer users to find disks misplaced for years and to open the files exactly as they were created years previously.
Related to the capacity to remember is the capacity to copy; once a digital file is recalled from memory it can be copied with a few clicks. The copy of a digital file is identical to the original, so the fidelity of digital information is not degraded as copies are made and as copies of copies are made. Further, copies can be made with a marginal cost that approaches zero; once a computer system is purchased and powered and it contains sufficient space to store the file, saving copies of files adds nothing to the expense of the system.
The effectively infinite memory of computers can be applied for many tasks in education. A virtual classroom can provide an archive of a student’s experience. Students enrolled in Advanced Biology (for example) can access curriculum materials and assignments that were part of Introductory Biology to review as necessary. The details of homework assignments can be accessed online indefinitely (at least until students or their parents realize missing work is threatening to result in a student having a failing grade on a report card).