The mother - named only as Juana F.F - approached the male teacher outside Turó de Roquetes school in the Nou Barris neighbourhood of Barcelona, shouting "son of a bitch" and threatening to kill him on October 7th 2014.
She then hit him "repeatedly across the head" with her handbag according to La Vanguardia.
The man suffered a cut to his left ear which lasted ten days, as well as anxiety and depression after the assault, which "prevented him from carrying out his job as normal", he told the court.
The judge did not credit the teacher's claims, ruling that "it cannot be concluded that a blow over the head with a handbag could cause a mental injury".
The mother was sentenced to one year in prison and fines of just under €500.
While the motive behind the assault remains unclear, court documents revealed that the teacher had been kicked by the woman's nine-year-old son while trying to take him to the headmaster's office the previous day.
Several other teachers had to intervene to stop the boy from kicking his teacher.
The mother was also ordered to pay €314 compensation to the teacher, as well as a fine of €6 a day for a month.