The National Council on Teacher Quality, an advocacy group, is to issue a study on Thursday reporting that most student-teaching programs are seriously flawed. The group has already angered the nation’s schools for teachers with its plans to give them letter grades that would appear in U.S. News and World Report.

The council’s report, “Student Teaching in the United States,” rated 134 student-teaching programs nationwide — about 10 percent of those preparing elementary school teachers — and found that three-quarters of them did not meet five basic standards for a high-quality student-teaching program.

When the U.S. News rankings are published, the student-teaching programs will count for one-fifth to one-third of an education school’s grade, according to Kate Walsh, president of the council.

“Many people would say student teaching is the most important piece of teacher preparation,” Ms. Walsh said. “But the field is really barren in the area of standards. The basic accrediting body doesn’t even have a standard for how long a student teacher needs to be in the classroom. And most of the institutions we reviewed do not do enough to screen the quality of the cooperating teacher the student will work with.”