BISMARCK (AP) - A worsening North Dakota teacher shortage is forcing schools to increase class size and hire teachers who are not fully qualified, a coalition of education groups said Thursday.

The North Dakota Education Association released a survey on teacher recruitment and retention that found many school districts facing a growing number of teacher vacancies.

Out of 258 school districts, 184 responded to the group's second annual survey. Forty-one school districts reported a total of 73 unfilled teaching positions at the beginning of the school year.

Areas hurting most for qualified instructors are special education, counseling, science, music and business, the NDEA survey said. Even principals are in high demand the survey found.

The survey also found more teachers this year did not return to their schools. The number increased to 619 this year compared with 549 teachers last year.

The survey spotted another troublesome trend in the number of teachers who are retiring. In 1999, survey respondents reported that 135 teachers had retired that school year. This year, the number went up to 208, a 54 percent increase.