What Chicago Academy of Fine Arts cartoonist taught Walt Disney?

Walt Disney attented the Chicago Academy of Fine Arts, but I've found nothing to indicate Ub Iwerks went to school there.

'Ub Iwerks was born in Kansas City, Missouri on March 24, 1901. While that's when his life started, the real adventure began in 1919 when at the age of 18, Iwerks got a job working for a company called Pesman-Rubin Commercial Art Studio. His job was to use the artistic skills he had mastered while growing up to produce work for Pesman-Rubin clients. Soon more people were being hired, including a young man named Walt Disney. It wasn't long before Iwerks and Disney formed a bond.'

http://www.digitalmediafx.com/Features/ubiwerks.html

Born in 1901, Walt Disney attended the Chicago Academy of Fine Arts at night while still in high school around 1917-1918. Tex Avery was born in 1908 and took courses at the Art Institute of Chicago after graduating high school in 1926. By that time, Disney had already been in Hollywood three years and had started his own company.