Whiling away the day. Summer reading program captures brother and sister. CHILDREN'S BOOKS

IT'S the end of a long, hot summer day, and I can't believe where my children are. Not squabbling or restlessly opening the refrigerator. Not even sprawled in front of the television set. No, they're reading. That's right - reading. Seven-year-old Kate is curled up on my bed and laughing out loud at her story. And 11-year-old Matt is in his room, deep in the adventures of the Hardy boys.

Now before you conclude these kids are geniuses - or wimps - let me assure you it wasn't always so. In fact, I keep looking up from my word processor and listening to the contented silence around me in happy disbelief.

My kids - at last - are readers. And it's all because of an amazingly simple activity - our Summer Reading Contest, now in its second year.

Kids who read, I'd always believed, become better students - more informed and generally more interesting people.

Besides, I wanted my children to experience the pleasure reading had brought me when I was a child. And everything I'd ever read promised that - if you read to children, enjoy books yourself, and don't allow much TV - they'll turn into readers themselves.

I was doing all that. But they weren't reading. Matt had always been a pretty good student, but was an active, energetic boy who spent every minute of free time in sports or outdoor play. Kate had learned to read that year in kindergarten, but she certainly didn't yet have the habit.

So our Summer Reading Contest was born.

On the first day of vacation last year, I taped the rules to the refrigerator. I'd written them in enthusiastic contest hype: ``Congratulations, Matt and Kate Daniel! Out of ALL the children in the universe, YOU have been chosen to participate in the INCREDIBLE 1987 SUMMER READING CONTEST!'' I typed it to make it look more official and decorated it all with pictures of prizes and screaming slogans like ``Money!'' ``Power!'' ``Brains!'' ``Prizes!''

The rules are simple.

To play, each child must read for 25 minutes a day, five days a week. And to win, all the children have to do is complete a certain number of books. When they finish a book, they tell me, and we add it to the list on the refrigerator.

Since frequent reinforcement seems better than one far-off prize, the prizes come at intervals - about every five or six books. The more the child reads, the more prizes he gets. The further he goes, the richer the rewards.

At the beginning, for example, the prizes are as simple as an ice cream cone or 7-11 Slurpee. But last summer's grand prize - for reading 28 books - was ``an all-expense paid trip to Disney World with an overnight stay in a motel!''

I also gave them lots of choices for the prizes at every level, which I think was one of the main reasons the contest worked. After 15 books, for example, they could choose between a night at the bowling alley with a friend, dinner at a restaurant, a sleep-over party with two friends, or a new beach float.

At 22 books, the choices included a $15 shopping spree in a toy store, a ride on a jet ski, an evening of mini-golf, or a snazzy new pair of sneakers.

Subtle and refined these prizes are not. But they are things the kids crave, and nearly every day I'd see them standing in front of the refrigerator greedily eyeing the next level and debating which one they'd choose.

From the first day, the kids were hooked.

I made sure there were lots of books around and asked a helpful librarian to guide me to sure-fire choices. ``The Read-Aloud Handbook'' was also a great source of good books.

I soon discovered that even the most thrilling book would turn Matt off if it were more than 100 pages long. If a book didn't click after the first few chapters, he wasn't required to struggle to the bitter end. Building character was not the point. Learning to love reading was.

Since the kids knew they had to read for 25 minutes each day rather than complete a certain number of pages, they didn't rush through, but settled into the books comfortably.

Soon they were reading more than the required time - at first just to win the next prize, but finally because they were actually engrossed in the book. It probably helped that they're not allowed to watch much TV.

How do they prove they've actually read the book?

For some reason, so far that hasn't been a problem. Kate often reads her books - which are short - aloud to me after she finishes them, which is a kind of proof.

Matt tends to discuss them after he's through - sometimes even turning me on to an author. Last summer he introduced me to Roald Dahl's wickedly funny stories, and I've also enjoyed a number of Kate's favorites, like Beverly Cleary's Henry Higgins series. I treasure the times one brings me a book and says, ``Try this one, Mom - you'll really like it.''

Last summer both children won the grand prize, and at Disney World Kate proudly told almost every ride attendant, ``I read 28 books!'' This year she kept her reading time, coming home from first grade and heading straight for my bed for 25 minutes of quiet recharging with books.

Matt, with a busy schedule of after-school activities and homework, read less. He still prefers soccer to books, but he no longer regards reading as a crushingly boring chore. And all through May he reminded me it was time to make up this summer's contest.

The reading contest didn't turn my kids into geniuses or solve all our family problems. But in a small but significant way, I think it changed our lives.

Matthew and Kate are proud of themselves and their accomplishments. They're at home in the world of books and have traveled that intensely personal and expansive journey out of self and into an imaginative universe.

As for me - I can come home from work, kick off my shoes, and relax with a book in the midst of a family - where for half an hour, at least, the only noise is the quiet turning of pages.