One key area where inflation is slowing down a little is the cost of sending a child to college. Tuition fees are still going up. But the important fact for trend-watchers is that the increase is not as big this year as it was last year and the year before.

The average cost of sending a child to college in September will rise only 4.3 per cent, according to a study by the College Scholarship Service. That's the lowest average in five years. Last year, costs went up 7.5 per cent, and the year before, 8.8 per cent. In 1973-74, costs were rising an appalling 17.3 per cent.

There is no guarantee that the rate of increase will continue to slow. It all depends on what happens to prices elsewhere in the economy. But the signs are good.

Another encouraging fact is that scholarship money is increasing far more rapidly than college costs. The total amount available for financial aid will rise about 11 per cent this year, on top of a 12 per cent increase last year.

With college enrollments on the decline, that means more money to spread among fewer students. A parent who is having trouble getting aid for his child may find it hard to believe that scholarship money is more widely available than ever before. But it is. The College Scholarship Service estimates that the amount of money given for all kinds of financial aid in the 1977-78 school year will be $10.3 billion dollars.

There is a real awareness on the part of financial aid officers that the middle classes need more help with tuition payments. Elizabeth Suchar, director of financial aid services for CSS, told my associate Anne Colamosca. If grant money isn't available, they're trying to help these students get bigger loans. "The colleges are beginning to realize that even higher income families have a problem nowadays," Suchar says.

State universities continue to offer the best value to parents on a tight budget, since they cost about 40 per cent less than a comparable private school. The table below shows the average cost next year for a student living on campus at various types of institutions (including tuition, room, board, books, transportation, and personal expenses):(TABLE) Type(COLUMN)Average Expenses Public 2-year(COLUMN)$2,550 Private 2-year(COLUMN) 4,015 Public 4-year(COLUMN) 2,906 Private 4-year(COLUMN) 4,811(END TABLE)

The highest tuition reported at any undergraduate institution is $5,500, at Vermont's Bennington College. With room and board added in, the yearly expenses at 16 schools will be over the $7,000 mark. Combined costs per year at Massachusetts Institute of Technology are $7,950; at Brown University, $7,630; at the University of Pennsylvania, $7,575; and at Stanford, $7,365.

For a rundown of the costs at some 2,750 colleges and other post-secondary institutions, write for "Student Expenses 1977-78," published by the College Entrance Examination Board. It costs $4, from College Board Publication Orders, Item Number 3179435, Box 2815, Princeton, N.J. 08540.