( CNN ) -- A whistle-blower whose research on athletes ' literacy caused a firestorm of controversy at the University of North Carolina is leaving , she told CNN on Monday . Mary Willingham said it 's her choice . She said she has n't yet turned in a final letter of resignation but simply informed her boss that she plans to leave before the end of the semester . `` It 's been a hostile work environment the entire year , '' Willingham told CNN . `` I stuck it out because I wanted to make good on promises to my students , but it has not been fun . '' UNC spokesman Joel Curran said he was aware of Willingham 's public comments , but he was `` unaware as to whether or not she has formally tendered her resignation . '' Willingham was one of the original UNC staff members to publicly call attention to a system of `` paper classes '' at UNC . She told the The News & Observer newspaper in nearby Raleigh that athletes were pushed into classes that required very little work and no attendance . This year , she told CNN that during the course of her research , she personally worked with athletes who were functionally illiterate . Her research was disavowed by the university . UNC : Experts find flaws in whistle-blower 's findings . UNC said three independent experts in adult literacy conducted a university-commissioned review of Willingham 's research and found flaws in her claims that some athletes were reading at elementary-school levels . Willingham 's research , described to CNN in January , was based on a sampling of about 180 athletes with whom Willingham worked during an eight-year period . Each had taken a 25-question reading vocabulary test on the Scholastic Abilities Test for Adults . The aptitude test used by many universities to gauge the learning level of incoming students . Last month , a Washington whistle-blower group wrote a letter to UNC , demanding the university apologize to Willingham and launch an investigation into the way it says she has been publicly smeared , most specifically by Provost Jim Dean . The group said it was possible that North Carolina whistle-blower laws were broken . Since the CNN report aired , UNC has asked for a new investigation into the yearslong paper class scandal , in which student-athletes allegedly were taking classes in which the only requirement was completing a single paper . Attorney Kenneth Wainstein , who had worked at the U.S. Justice Department for 19 years , is reviewing whether it was widely known among staff in athletics that players were sent to no-show classes where little or no work was required . U.S. Rep. Tony Cardenas , D-California , is also demanding the NCAA address why UNC was never sanctioned . Willingham told CNN that the paper classes were widely known and talked about in athletics , where she worked for seven years . She also said the paper classes were used to keep eligible some of the athletes who were reading at low levels . Some college athletes play like adults , read like 5th-graders .
Mary Willingham said her research exposed some athletes ' poor reading ability . The University of North Carolina countered that experts found her results flawed . Willingham said she stuck it out this long because of 'promises to my students ' She said she has n't turned in a final letter of resignation but told her boss of her intentions .