The 23,000 seventh and ninth graders in Prince george's County will be retested on part of a statewide achievement examination next month because some were accidently given actual test questions during a pratice session.

The retesting in the language arts sections of the Iowa Test of Basic Skills, planned for the last two weeks of April, will cost the county $8,950, according to county school spokesman John R. Aubuchon.

He said the problem started when two teachers inadvertently gave some of their students actual questions during a practice. The two teachers then "shared" the practice questions they had used and they were more widely distributed for use in other practice sessions.

"We don't know how many students took the test" after seeing the real questions in practice, Aubuchon said.

He said an investigation has determined that the two teachers' action was "accidental and not malicious."

Aubuchon declined to disclose the names of the teachers, the school or schools to which they are assigned, or what actions, if any, would be taken against them.

The students did not know they were taking real test questions during the practice session, Aubuchon said.

"Obiviously we will look at the manner in which (the test) were handled. There may possibly be a reevaluation of our prosedure," Aubuchon said.

The Iowa tests are given annually to all third, fifth, seventh and ninth grade students in Maryland in an attempt to determine their academic achievement and assess areas of individual tutorial needs, according to Aubuchon.

After the 75-minute language arts section of the test given several weeks ago, "some of the students told their teachers that they had seen the same questions on practice sessions," Aubuchon said.

An investigation headed by Deputy Superintendent Allan I. Chotiner determined what had happened, he said.

According to Ben Creson, spokesman for the Maryland Board of Education, the Iowa tests are distributed to the principal of each school, who must keep them under lock and key. The principal may then desinate a teacher to be responsible for the tests, if he chooses.

Creson said it was a "logical" to assume that the tests were inadvertently distributed by either a principal or a teacher-designee in one of the Countys 42 junior high schools.