Tools menu reference
Tools|Sort students|Unsorted
The Sort students unsorted command affects the student ordering when sorting alphabetically. Normally this menu item does not have a bullet to indicate the students are sorted. If the menu item does have a bullet, the students are shown in the same order they were entered in the markbook.
Choose the command to show the students in the order they were entered into the markbook. This command is useful when tagging students in the order that they were entered into the markbook. After importing a list of students, by showing the students as unsorted, they are shown in the same order they were in the imported list.