A jury returned majority guilty verdicts.
The jury failed to agree on a further 42 charges.
The accused, now aged 73, who cannot be named for legal reasons, pleaded not guilty to 72 charges of indecently assaulting the boys on dates between September 1978 and June 1981.
Judge John Hannan remanded the former teacher in custody.
During nine days of evidence, 13 former students gave evidence.
The guilty verdicts were returned in relation to six of the boys when they were in fifth and sixth class between 1978 and 1981. After deliberation of 10 hours over three days, the jury of seven men and five women brought back their verdicts.
The assaults were carried out in a classroom and corridor. Evidence was given how the teacher would walk through the aisles of the classroom, approach boys individually at different times and place his hands inside their pants and feel their genital area.
After returning their verdicts, Judge Hannan told the jury that it was a difficult and challenging case to listen to.
John O’Sullivan, prosecuting, asked that the case be put back to December 9, for mention, with a view to obtaining an early date for sentence.
He needed to take instructions from the DPP in relation to the 42 counts on which the jury disagreed.
Judge Hannan ordered that the teacher not be named at this time. Andrew Sexton, defending, said the teacher was not seeking to remain on bail and he was remanded in custody to December 9.