The following were among actions taken at the Sept. 21 meeting of the Prince George's County Board of Education. For more information, call 952-6000.

MISBEHAVIOR REPORT -- Superintendent John A. Murphy reported that serious incidents of student misbehavior and crime declined by 35 percent in the past four years, from 2,666 incidents in the 1983-1984 school year to 1,731 incidents in the 1986-1987 school year. He attributed the decline to the school system's strict discipline policy.

All incident categories showed a decrease, except for a 5 percent increase in the number of reported sex offenses and a 23 percent increase in incidents of trespassing on school grounds, according to a study done by the system's Department of Pupil Services.

The study showed the incident rate per 1,000 students decreased by 32 percent during the four-year period, from 25 incidents per 1,000 students four years agoto 17 incidents per 1,000 students last year. The study concluded that tough policies, such as expulsion for students caught fighting at any Prince George's school or schools in other counties, and not a decline in enrollment, contributed to the overall decline.

The study showed alcohol incidents dropped from 29 to nine incidents, bomb threats dropped from 488 to 313; drug incidents dropped from 285 to 142; and weapons incidents dropped from 150 to 102 during the four years.

The study showed that reported sex offenses increased from 21 to 22 incidents and trespassing incidents increased from 97 to 119 in four years.

CAPITAL IMPROVEMENT PROGRAM -- The board unanimously approved the superintendent's recommended $158.4 million Capital Improvement Program that includes plans for renovations and improvements at 19 schools over the next five years.

The program asks that the state pay $83.4 million and the county pay $75 million of the cost of such improvements as adding temporary classrooms at overcrowded schools; replacing old heating and air-conditioning systems, roofs, pavements and leaking fuel tanks; and constructing a central equipment storage garage and a second gym at Eleanor Roosevelt High School.

Other schools slated for improvements are: Bladensburg Elementary, Bladensburg High, Bowie High, Bradbury Heights Elementary, Buck Lodge Middle, Cheverly-Tuxedo/Happy Acres Elementary, Croom Vocational, Fairmont Heights High, Francis Scott Key Middle, Frederick Douglass High, Greenbelt Center Elementary, Greenbelt Middle, Largo High, Laurel High, Northwestern High, Oxon Hill, Suitland High and Surrattsville High.

HILLCREST HEIGHTS ADDITION -- The board agreed to take bids on a contract to transport a temporary six-classroom building from Montgomery County to Prince George's County, where it will be attached to the overcrowded Hillcrest Heights Elementary.

School officials said Hillcrest Heights, which is a Milliken II school, has 570 students and more than 20 students per classroom. Milliken II schools are required to have classes no larger than 20 students.

Transporting and installing the addition will cost $163,000. The state will pay $130,000 of that.

SOUTHERN AREA SCIENCE CENTER -- The board approved a motion by member Paul R. Shelby to begin plans for a student science center in the southern part of the county, similar to the Howard B. Owens Science Center in Lanham.

Shelby said the southern area needs a science center so students do not have to ride long distances to Lanham. The board agreed to begin plans for the new center in 1989. The Owens center, which has special scientific equipment and computers, is designed to instruct students at all grade levels in special science projects.