Answer:
My teacher told me to read so that I might understand.
Explanation:
According to the Oxford dictionary a conjunction is "a word used to connect clauses or sentences or to coordinate words in the same clause."
The conjunction "so that" is a subordinating conjunction. Subordinating conjunctions are usually used to link the main or independent clause to the subordinate or dependent clause.
Hence, inserting the subordinating conjunction, the sentence should read; "My teacher told me to read so that I might understand."