Conversation so far:
What subject did Ludwig Mies van der Rohe teach while as an educator?
He played a significant role as an educator, believing his architectural language could be learned.
At which school did Ludwig Mies van der Rohe teach at?
The Illinois Institute of Technology in Chicago.

Question: What year did he begin teaching at the Illinois Instite of Technology?
Self-contained rewrite: What year did Ludwig Mies van der Rohe begin teaching at the Illinois Institute of Technology?