The teacher, identified as N Balakrishnan is the Vice-President of the Kerala School teachers Association, police said.
Chandy had suffered minor injuries on his forehead on Sunday when LDF protestors pelted stones when he was on his way in a car to the police grounds here to attend a function.
The LDF had distanced from the attack holding that physically targeting the Chief Minister was not part of its campaign.
LDF has been pressing for Chandy's resignation in the backdrop of solar panel scam which pertains to financial cheating of several people by promoters of a private firm offering them solar energy solutions.
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LDF has been alleging that the fraudsters had the support of Chandy and his office. Though the government had ordered a judicial probe, LDF refused to give up their demand.
Meanwhile, Kannur District Congress Committee leaders observed a one day fast here today, in protest against the attack on Chandy.
CPI(M) Politburo member and former minister Kodiyeri Balakrishnan told reporters at Thalaserry that LDF would continue their protests during the 'people mass contact programme' by Chandy here on November 18.