The jury at Lincoln Crown Court took just over an hour to find David Thomas, 68, not guilty of the five charges he faced.
Thomas, a former teacher at Bowl Alley Lane Junior School in Horncastle, had denied all the allegations - telling the jury he did not act inappropriately towards the two complainants.
The court heard Thomas was interviewed by police at Skegness police station in July 2020 and answered all the questions put to him.
Thomas told the jury he felt bewildered by the allegations and chose not to have legal advisors when he was interviewed by the police because he had nothing to hide.
The court was told Thomas trained as a teacher in Lincoln after previously working as a police cadet and started work at Bowl Alley Junior School in September 1975.
He remained at the school until 2016 when he retired at the age of 63 after 41 years service.
During his time working at the school, Mr Thomas said he at various times helped out with the football and netball clubs, school plays and the school library.
Four of the charges related to one alleged victim and were alleged to have occurred between February 1980 and February 1983.
She alleged one of the incidents occurred in a cupboard at the back of the school gym.
When asked about the allegation Mr Thomas replied: “No, no. All I can say is no.”
Mr Thomas said if anything he regarded himself as strict and stand-offish as a teacher.
Thomas was also accused of one offence of indecent assault against a second alleged female victim aged under 14.
That offence was alleged to have occurred between September 1982 and September 1984.
Giving evidence the alleged victim claimed Mr Thomas rubbed himself against her after intervening in a playground altercation and dragging her into his classroom.
The woman said she made complaints to the authorities in 2008 and 2013 but was told “it’s my word against his.”
But when questioned about the incident Mr Thomas said there would have been two members of staff on duty in the playground and a female member of staff would have intervened in a fight between two girls.
The jury heard large windows also faced out from Mr Thomas’s classroom.
Mr Thomas said: “She must have been imagining this,” adding, “I have no recollection, it didn’t happen.”
Thomas, of Harding Close, Sutton on Sea, denied two serious sexual offences and three charges of indecent assault.