With the kids back in school, millions of parents across the country are looking at their family computers and asking the old question: What kind of educational software should I buy to justify spending a couple of grand on this gadget? There are a lot of answers. But at the outset, consider that most people who buy computers use them for word processing. And that brings us to the most important single "computer" skill your child can learn: typing. Actually, it was called "typing" when I learned to do it thirty-something years ago on a relic called a typewriter. Today it's called "keyboarding."

But the basic skills are the same and they are even more important now than they were then because so much of today's work is done at the keyboard. Learning how to type properly is critical for several reasons. While most kids and adults can learn to hunt and peck on their own, real typing speed depends on proper technique. And speed is important because yo9ungsters should learn how to think and compose at the keyboard.

The problem is that we can think much faster than we can put words down on paper. Just watch a child struggle with a handwritten assignment. He knows what he wants to say, but it takes him so long to get it down, and he has to concentrate so hard on the mechanics of writing, that his thoughts often get lost in the process. While we will never be able to completely close the gap between thought and recording speed, a fast typist comes a lot closer than a slow one, and even a slow typist can do it a lot faster and more neatly than someone writing long-hand.

There are a couple of ways to learn how to type. The best is to take a good typing course. I was lucky because the school system I attended required everyone to take a full year of typing in the ninth grade. In retrospect, it was the most valuable single course I took. Few school systems require typing today, although they should, given the importance of computer keyboards in everyday life. But most do offer keyboarding courses, and they are definitely worth taking. Besides teaching basic typing skills, they teach students how to compose and format business letters, term papers and other documents.

I know many upscale parents would rather have John or Jane spend their time in a course on advanced thermonuclear physics, but at the high school level, they will get more in the long run by learning a skill that will carry them through all the advanced courses they will take in the future. For those who want to learn on their own, the computer itself provides plenty of opportunities. Typing tutor programs have been around for more than a decade, and the latest versions offer all sorts of graphics, games and sounds to spiff up the basic drills and exercises.

While they are entertaining, these multimedia goodies do not add much value in my book; in fact, watching a game while you are trying to type can be downright distracting. But they do provide some comic relief from the drudgery, and they may provide a hook for younger children who might otherwise not be willing to concentrate on the task at hand.

At their core, typing programs rely on standard teaching techniques that have been developed during the past hundred years, taking you from beginner to advanced levels with a series of drills and timed typing tests. What makes the difference is how they analyze and track your progress.

Of the three popular typing programs I tried out recently, Mavis Beacon Teachers Typing from the Software Toolworks is still the standout, as it was when I last looked at typing software a couple of years ago.

The latest release for IBM-compatibles, Version 3, offers a variety of new features, including fancier graphics, better lesson tracking, MIDI music, and practice text from The New Grolier's Encyclopedia and Newsweek.

Glitz aside, Mavis is the most sophisticated of the three in terms of analyzing your typing skill and providing customized lessons, and it offers 20 different charts and graphs to track your strengths and weaknesses. Its "guide hands" on a keyboard screen display are still the best technique I have seen to illustrate proper fingering. Typing for Today from Interplay Productions Inc. is interesting largely because it will "speak" each letter as you type if you have a sound card and even dictate an entire text passage while you see it displayed on the screen. This is particularly good practice for those who may have to transcribe dictation.

The program's basic instruction is solid, and I actually prefer its method of scoring typing speed.

Mavis Beacon uses the old system I learned under in the days of manual typewriters, when original accuracy was all-important because mistakes were messy and difficult to correct. In its timed tests, Mavis prohibits students from correcting mistakes and subtracts a number of words per minute from the student's score for each mistake it finds.

Typing for Today, on the other hand, recognizes that computers allow you to go back and correct mistakes easily. It only counts a mistake if you don't catch it and correct it, and your score is the actual number of correct words per minute that you produce.

It also features a cute little typing game involving a knight who faces different opponents, but I found it hard to concentrate on who was slugging whom with a sword and concentrate on my typing at the same time. Come to think of it, it's not bad practice for working in a newsroom.

If your kids were weaned on Nintendo games, you may want to start them off with Mario Teaches Typing, also from Interplay.

The CD-ROM version, which I tested and Ben, my 11-year -old, likes, turns typing into a noisy you-know-what, complete with old Mario and his friends Luigi and the Princess bouncing and bonking their way through strange little world. Their speed, of course, depends on how fast and accurately you type.

With the CD/ROM version, you get a wonderfully sculpted, 3-D Mario who pops up to offer help and gratuitous comments in a vaudeville accent that ought to be the subject of a lawsuit by the Italian-American Anti-Defamation League.

When and if your kids get tired of the pyrotechnics, there is a solid typing tutor underneath, with standard lessons and enough content to get your youngsters firmly established.

For information on these programs, contact The Software Toolworks Inc., 60 Leveroni Court, Novato, Calif. 94949, or Interplay Productions, 17922 Fitch Ave., Irvine, Calif. 92714.