The display shows one of 100 library 'books' containing both text and pictures.
Clicking on exit will take you back to the main library 'shelves' where another 'book' can be selected (or the library left).
Clicking on the direction arrows will allow you to browse other 'books' in the library without going back to the main 'shelves' as follows:
LEFT: Takes you to the 'book' to the left of the current book' on the same 'shelf'. If there is no 'book' to the left then the next 'book' is taken as being the one to the extreme right on the same 'shelf'.
RIGHT: As for left, but in the opposite direction.
UP: Takes you to the 'shelf' above at the 'book' immediately above the current 'book'. If there is no 'shelf' above the current 'shelf' then the bottom 'shelf' is used.
DOWN: As for up, but in the opposite direction.
NOTE: If the shift key is pressed when UP (or DOWN) is clicked, the effect is to take you to the 'book' on the shelf above (or below) that covers the topic you reached in the most recent test. (The 'book' with a green marker underneath.)
