The parents of the 15-year-old Perry Hall high school student had allegedly found dozens of texts between the 42-year-old man and the girl.
Police described them as emotional and inappropriate.
The girl's mother told the police but police said no crime had been committed.
The teacher then showed up to the home unannounced Thursday morning to speak to the father.
After the father asked him to leave and the teacher refused, the father struck him with a baseball bat.