Here's why it's difficult to know:
* Limited Records: Educational records from the 1850s (when Edison would have been in school) are often incomplete or lost.
* Focus on Basics: Education at the time was primarily focused on reading, writing, and arithmetic. Language learning wasn't as common as it is today.
However, we can make some assumptions:
* English: As an American child, Thomas Edison would have learned English as his native language.
* Limited Exposure: It's unlikely he would have had exposure to other languages at that age, unless he had a family member who spoke another language.
If you're interested in learning more about Thomas Edison's life and education, you can research his biography or visit the Edison National Historical Park.