Additional District and Sessions Court Judge S Sivakadatcham handed out the sentence to Sivanesan working in a government high school at Surakudi in the district on Wednesday.
He pronounced the verdict and slapped a fine of Rs 5,000 on Sivanesan.
Hailing from Puducherry, the teacher assaulted the Class 6 girl during the lunch break on August 4, 2016, when she had visited him in the staff room to get her notebook corrected, according to the prosecution.
The student had suffered severe stress and injuries. Her parents got to know about the incident only on August 11, they added.
On a complaint, Tirunallar police arrested Sivanesan.
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