More than half of respondents in a recent survey said they had noticed corrupt practices at educational institutes.
The survey covered 294 school administrators, teachers, students and academics.
The most common form of wrongful practice is teachers or school administrators spending their work hours on something else, according to the survey.
Other common wrongful behaviours are the use of government resources for personal interest, nepotism, and abuse of authority, the findings show.
Rungnapa Nutravong, an expert at the Office of Basic Education Commission (Obec), released the findings at a press conference yesterday.
"Greed is the foremost cause," she said, adding that poor financial conditions, lack of ethical leaders, ambition and pressure were among the common causes.
"Our study shows the best way to tackle corruption at educational institutes is the inculcation of ethics and honesty," she said.
Rungnapa is a participant in a psychological-security course for school administrators.
Obec adviser Pojaman Pongpai-boon said her office had conducted the course in collaboration with the Applied Psychology Institute.
"We aim to ensure a corruption-free environment at schools," she said. "Also, we seek to inculcate morality in students."
She said executives from 225 schools had attended the psychological-security course in its pivotal phase.
"We expect executives from 3,000 schools to join this course next year," she added.
A report by the National Anti-Corruption Commission (NACC) showed as many as 1,387 corruption complaints were related to questionable practice at the Education Ministry between 2000 and 2005.
The Education Ministry ended up in second place - behind the Interior Ministry - when it came to the number of corruption complaints filed with the NACC.