I had one of these as a kid; the slow way it drew the graphics onto the screen [1] for a new activity was an aesthetic in itself, like a coloring book being drawn and colored in before your eyes, a perfect loading screen for kids.
Wikipedia notes: The system will "draw" images by filling in areas of the screen with color one line at a time; it is not known whether this is an effect employed for the student's enjoyment or if it is due to the slow processing time of the system.