Instructions
Head to the north end of the hallway and examine the riddle on the slate. Two lines in the second paragraph read: "Young and old lined up / In order of age." Keep this in mind; it's the key to solving the puzzle.
Return to the other end of the hall and read the slate near the keypad. It's a list of peoples' names. Next to each of the five names is a number signifying that person's age. Rearrange the names from youngest to oldest. The proper order is: Albert Lords, Lydia Findley, Edward C. Briggs, Roberta T. Morgan, Trevor F. White. You'll notice that the first letters of the people's first names spell out the word "ALERT." This is the code for the keypad.
Examine the keypad on the wall next to the door. Enter the code "ALERT" on the keypad to unlock the door and complete the puzzle.