A former South Yorkshire teacher asked pupils to undress at his home and measured their genitals for what he claimed was a 'development study'.
Denis Hays was working at Greasbrough Primary School in Rotherham between 1975 and 1977 when he asked youngsters who were leaving the school to attend his home for what he said was a 'child development study', a disciplinary hearing was told.
The 72-year-old admitted asking three pupils, then aged between 11 and 14, to undress before measuring their penises.
He claimed the measurements were taken for a private study which he hoped would increase his chances of promotion, but this study was not linked to any school or other organisation and he did not tell his school or the secondary school the boys were attending about what he was doing.
A professional conduct panel of the National College for Teaching and Leadership found his motivation was at least in part sexual and he had been trying to keep the details of the study from others in the knowledge it was inappropriate.
The panel found his behaviour had amounted to both unacceptable professional conduct and conduct that may bring the profession into disrepute. It recommended he be banned from teaching indefinitely, a sanction which was approved by education secretary Justine Greening.
Mr Hays never completed the study or published any findings, claiming he had abandoned it after his personal cicumstances changed. The details only came to light in 2015 when one of the pupils reported the matter to police.
The panel said the former teacher, who described his actions as 'naïve' and said he should have had another adult present to protect himself and the children, had failed to grasp the seriousness of his conduct.
In a written decision, it stated: "(The panel) considers that his actions had the potential to harm the pupils involved in the study. The panel also felt from Pupil A’s live evidence, that Mr Hays relied upon his status as a respected and trusted teacher in order to have the boys participate in the study; it was noted that Pupil A had felt keen to please Mr Hays. The panel therefore felt that Mr Hays had exploited his position in conducting his sexually motivated behaviour."