Shouldn't it be 4th tone of 教？
jiāo - is when 教 is a verb. 她教我中文
jiào - is when 教 is part of a noun: 教育，请教, so usually when it's the 4th tone, 教 is not used alone, but as a part of a phrase.
She taught me chinese was marked as wrong
Mandarin should be accepted too...