Sixteen armed robberies, including one in which a teacher was held up in a high school classroom and another in which a drive-in bank window was held up by a man who walked up with a gun, were reported in eight hours in Washington yesterday, as the robbery rate continued rising.

Among the locations where the crimes occurred between 12:50 and 8:50 p.m. were a parking lot near Dupont Circle, an apartment house hallway in far Southeast, a supermarket in Brookland and a convenience food store on Connecticut Avenue.

A total of four persons were arrested and charged with robbery in connection with two of the incidents, which came as police began a program of sending special patrols onto the streets for the holiday season in an effort to hold down the crime rate.

The 16 armed robberies in eight hours yesterday compares with an average of about 13 a day recorded for the year. For the three months ending in September, the rate of armed and unarmed robberies rose to an average of more than 26 a day.

Lt. James Waybright of the robbery squad said robberies have been increasing steadily and "haven't reached a plateau as yet." r

The bank holdup occurred at the Riggs Bank branch at 4100 South Capitol St. The teacher was robbed of rings and a watch by a man with a gun who invaded a classroom at Chamberlain High School at 14th Street and Potomac Avenue SE.

Earlier, Forrest V. Thompson, 30, of Falls Church was shot and killed in his parked car at Eighth and H Streets NW about 12:15 a.m. in what police said was an apparent robbery.