Seven defendants in the fraud case appeared before U.S. District Judge John Fowlkes. Lawyers for five of them requested new hearings where their clients could change their pleas to "no contest" or guilty.
Attorneys for two other defendants said they needed more time to review discovery in the case and set new report dates.
Prosecutors say people were paid to take Praxis certification exams on behalf of current or aspiring teachers in Arkansas, Mississippi and Tennessee over a 15-year period. The teachers then allegedly used their passing grades on the exams to get jobs in public school systems in the three states.
Those who have been charged with mail and Social Security fraud in the case are either accused of taking the tests in return for payment, or they are teachers accused of hiring alleged ringleader Clarence Mumford Sr. to arrange for someone to take the exams for them.
Prosecutors have said that dozens of people were involved in the scheme. Six defendants already have pleaded guilty in the case.
Mumford, a longtime Memphis-area educator who has pleaded not guilty to more than 60 fraud and conspiracy charges, has a change-of-plea hearing later this month.
Authorities say the scheme, which allegedly ran from 1995 to 2010, affected hundreds, if not thousands, of public school students who ended up being taught by unqualified instructors.
Mumford is accused of creating fake driver's licenses with the information of a teacher or an aspiring teacher and attached the photograph of a test-taker. Prospective teachers are accused of giving Mumford their Social Security numbers for him to make the fake identities.
Mumford would get a fee between $1,500 and $3,000 to send one of his test ringers with fake identification to the Praxis exam, prosecutors said.
Educational Testing Services, which writes and administers the Praxis examinations, has said the company discovered the cheating in June 2009, conducted an investigation and canceled scores. The company began meeting with authorities to turn over the information in late 2009.