She is trying to play the Gershwin classic "Summertime." A tricky chord progression on the "Yo' daddy's rich" phrase has stopped her, and with each wrong note, her jaw clenches a little tighter.

Someone tries to help her along by humming the tune. He is asked to be quiet in no uncertain terms; the rest of us squirm with embarrassment as the struggle between woman and keyboard continues.

The battle finishes in favor of woman. The player -- a 40-year-old housewife -- returns to her seat with words of encouragement ringing in her ears. "God," she mutters to no one in particular, "it was so much better at home."

The course -- "How To Play the Piano Despite Years of Lessons" -- is designed for the adult piano dropout determined to make one last stab at what might have been a frustrating pastime of youth.

There were 15 of us in Susan Yentis' University of Maryland class when we began. In this, our fifth of eight weekly classes, the number has thinned to 10 stalwarts. Our median age is 41. We have nothing in common but a certain desire to play popular music on the piano and a resolve to reenter -- as adults -- a domain we knew only as recalcitrant children.

Yentis, 34, looks out at the class. At one time her blond cheeriness had reminded me of Glinda the Good in "The Wizard of Oz." Now her bright smile brings to mind a shark I once saw in the Baltimore Aquarium.

"Okay, Clay," she says with a predatory grin. "Walk on up there and show us what you've done this week."

Making the long walk to the front of the class, I remember another time I played the piano in public. I was 16 and playing a piece by Bach. I lost my place in the middle of the recital and left the stage near tears, determined never to touch a piano again. Why didn't I keep my promise?

"Smoke Gets in Your Eyes" is the piece I chose for the class and had worked on for two weeks. I have always liked the tune infinitely more than the Bach of my adolescence and Jerome Kern's melancholy lyrics are bound, I figure, to make me the hit of late-night parties.

I sit down to play and look out at my audience; they are staring fixedly at their feet . . . Always difficult to look a condemned man in the face.

I start to play: "They asked me how I knew . . ." -- stay calm, big fella -- " . . . my true love was true?" Looking pretty good . . . Everything is fine right up to the second section. But when I reach "Yet today, my love has flown away," hand-eye coordination also flies away. My fingers become a tangle of sweaty digits. I should never have tried the tricky cross-hand technique (lesson three) for this song.

Yentis smiles, and helps return my balky fingers to their proper areas on the keyboard. When I finish the piece and return to my desk she again is Glinda the Good and all is right with the world. I turn to the man seated next to me and mutter, "You really should have heard me at home. It was so much better."

The How To Play the Piano Despite Years of Lessons manual, conceived by New York journalist Ward Cannel and written with the late Fred Marx, a professional pianist, is based on an amazing concept: If you are human, you are able to make music at the keyboard. It shouts proudly, "Every man's a musician" while doing away with scales, exercises and other drudgeries that keep good folk away from the keyboard.

Writes the late Norman Lloyd, former director of education at Juilliard, in his introduction to the witty and cheeky text: "This is a subversive book . . . It has found one of the fundamental truths about music: As ye fool around, so shall ye find."

For too many years piano study has brought to mind images of beleaguered boys and girls slogging through Czerny exercises on Saturday mornings. The "Despite Years of Lessons" approach is keyed to, first and foremost, fun.

Says the last chapter of the book about "How To End a Number":

"One trouble with a lot of books about how to play the piano is that they never tell you how to stop playing the piano. That is, you don't find out how to end a number until it is too late and you are removed bodily from the piano bench and wrapped in cool, wet sheets."

You won't read anything like that in Hanon -- The Virtuoso Pianist.

According to coauthor Channel, rote learning is the primary enemy in music-making. "This course is not touch-typing at the piano. To learn to make music at the piano, one must acquire knowledge instead of wasting time on boring exercises."

One of the first things taught is "the basic skeleton": a simple melody line for the right hand, accompanied by an alternating bass-chord combination on the left. Although the basic skeleton is pretty boring, its virtue is that with mastery, one can play almost any popular tune that comes along: particularly useful for hambones who compensate for the skeleton's shortcomings by singing lustily.

The rest of the course is devoted to camouflaging the skeleton with increasingly devious methods: arpeggios, crossed-hand playing and a variety of rhythmic alterations. These techniques, in turn, form the basis for musical styles ranging from waltz and rumba to cocktail music.

But lest anyone get the idea that the course will, overnight, turn you into a Bobby Short, beware: As pleasant as "Despite Years of Lessons" can make life at the keyboard, piano playing is a skill, and, like any skill, its mastery requires a lot of plain, dumb, hard work. The course tries, however, to devote the work to making music, rather than numbing the mind with finger-development.

It is our last class meeting. The woman steps to a University of Maryland piano in front of 10 people. She looks evenly at her audience and declares, "I will now play "Summertime." There is steel in her words.

"Summertime and the living is easssssy." There is silence in the classroom. "Fish are jumpin' and the cotton is high." She sails perfectly through the first phrase and now faces her moment of truth. When she slows down at the dreaded "Yo' daddy's rich" phrase, I stifle a desire to help by singing along. Susan Yentis stands, no doubt preparing to jump in should things get uncomfortable.

The woman at the keyboard plays the chord progression with cautious finesse, as if driving expertly around a pothole. We thrill to her victory and she proceeds. "One of these mornings you're gonna rise up singing, gonna spread your wings and take to the sky . . ."

As the last phrases of "Summertime" drift into the night, the player leaves the bench and we celebrate yet another victory of woman over musical instrument. The applause is long and loud as she goes back to her chair. Seated next to me, the conquerer turns with a look of triumph and says, "God, it was so much better at home."

"How To Play the Piano Despite Years of Lessons" is offered in the Washington area at the University of Maryland and at Montgomery College. For information on other locations, write: The Piano Consortium, Sixth Floor East, 200 Park Ave., New York, N.Y. 10017.