At a difficult time of year for its supporters, a school bond issue goes to the voters of Fairfax County next Tuesday. The danger, of course, is that opponents may be more likely to show up for this special referendum. In the long run, that could prove costly. But if the proposed $39.7 million issue is approved, the money would pay for seven new schools to be built in rapidly growing areas of the county, where officials note that the schools already are severely overcrowded. Also, renovations would be made on a special-education center, four elementary schools, two intermediate schools and two high schools in various parts of the county.

Members of the school board and the board of supervisors are emphasizing the need for a turnout of supporters, since rejection surely would add to the eventual price tag of these improvements. In areas of the county where schools are anything but crowded, it may be hard to generate sympathy; still, the children in the rapidly growing parts need relief. If there has to be another referendum to try again for support, construction costs will be higher - and it's either that or take the money from the county's operating revenues and see what happens to taxes. So the sensible way - the approach that has won the support of the County Federation of Citizens Associations - is to approve the bond issue now.