Final answer:
Wan Shi Tong is a fictional character from the animated series Avatar: The Last Airbender who claims to know 'ten thousand things,' representing vast knowledge without a precise factual count.
Step-by-step explanation:
The question "How many things does Wan Shi Tong know?" does not pertain to an academic subject but references a fictional character, Wan Shi Tong, who is a spirit and the caretaker of the Spirit Library in the animated television series Avatar: The Last Airbender. In the show, Wan Shi Tong claims to know 'ten thousand things.' This character's vast knowledge encompasses many subjects, but the series does not provide an exact count beyond this phrase. Given the mythical nature of the character, an accurate, factual number cannot be provided. However, within the context of Avatar: The Last Airbender, Wan Shi Tong's knowledge is suggested to be immeasurable and all-encompassing.