REALITY DOESN'T always make it all the way to Capitol Hill. But last week, in an upset, it got as far as Rep. Ronald V. Dellums' (D-Calif.) hearing room. There, D.C. schools superintendent Vincent E. Reed told the congressman that schools are dangerous places that would benefit from having police patrol them. Mr. Deilums argued that the presence of armed police in schools was on impediment to the free and vigourous intellectual debate necessary for education and contrary to the spirit of it. As Mr. Dellums sees it, allowing police into schools might be inviting them to club any student who -- say -- reads Karl Marx aloud or offers an unpatriotic opinion.

Unfortunately, the reality of life in American public schools doesn't always conform to the Dellums' vision. The threat to free debate in classrooms comes not form security guards but generally from unruly students and from people who go into schools to rob, rape and sell dope. Some of those people simply walk around disrupting classes and intellectul activity daily. Some schols in this city have areas -- called "14th Street" and "The 'ghetto" -- where teachers and administrators don't walk. They have yielded those places to drug users, vagrants and class-cutters to keep their disruptive influence form spreading throughout the school.The severity of the problem in schools can also be seen in the number of crimes that occurred in District schools last year: more than 24 shootings and 1,000 robberies, assaults and thefts.

Supt. Reed told the congressman that the federal government could be of most help to the system he presides over by paying the cost of putting policemen in the schools. Short of paying to put added teacher in the schools, there really is nothing the federal government could do that would mean more to public education in this city. Freedom from fear of getting robbed, beat up -- or of having someone burst into your class wielding a knife -- is surelyh basic to an atmosphere where learning can take place. It is an alarming, even grotesque fact to have to have to point out -- but it is also self-evident.