A MERE 10 years ago, it was inconceivable that ballet would ever rival football in popularity. Yet today, its audience is bigger than ever, and is continuing to grow. Dance is no longer dismissed as "sissy" or esoteric. And it's interesting to note that in the children's books reviewed here, boys are encouraged every bit as much as girls. The next generation of dancers promises to be an exciting one.

However, all these books have a further point to make: Ballet is not all glamor; the occasional moments of exhilaration are paid for by years of sheer hard work.

On Stage, Please, by Veronica Tennant, is a charming story, beautifully illustrated by Rita Briansky. It holds its own against Noel Streatfield's classic Ballet Shoes and Dancing Shoes. Tennant, a principal ballerina of the National Ballet of Canada, writes with first-hand knowledge of her subject, cleverly weaving a considerable amount of information on dance into her plot. A young English girl arrives after she has seen her first ballet (cinderella). Despite the upheaval in her life, she is determined to become a dancer. After numerous setbacks she makes her stage debut as a fairy attendant (in the very same ballet) in Toronto. Tennant is a graceful writer and her enthusiasm for ballet is catching.

The Sisters Impossible, by James David Landis, offers a less encouraging view of a young dancer's life. His story centers on an ugly duckling who reluctantly takes up ballet in the wake of her haughty older sister. Fierce rivalries ensue at the school where efforts are made to intimidate the newcomer. This book evokes such a grim picture of life at dance class that it may well intimidate its readers into taking their exercise elsewhere.

Life at the Royal Ballet School, by Camilla Jessel, manages both to show the struggle and the rewards in dancing as a career. Four hundred 10-year-olds audition each year for 30 places at this prestigious school. The book, illustrated with excellent photographs by the author, is both fascinating and inspirational. As one teacher says, "It's up to you. Learn something the first time you are taught it . . . then do it better and better . . . not just the same -- better every time -- for FIFTY years. Otherwise there'll be others who do it better than you . . . and they will be the ones that get the best parts in the ballets!"

An overall look at ballet is given in The Magic of Ballet, by Catherine Dell. This is an extremely useful book, illustrated by drawings and black-and-white and color photographs, and includes a simple introduction to ballet and sections on technique, modern dance, choreography and design, as well as a look at the world's great companies and most popular ballets. It is a large, handsome volume and highly recommended.

If You Were A Ballet Dancer, by Ruth Belov Gross, explains ballet in question-and-answer form. It is amply illustrated, easy to read and informative.

My Ballet Class, by Rachel Isadora, is a distinguished and imaginative picture book. Isadora, a former ballet dancer, has captured perfectly the atmosphere and training of the studio. Her drawings are delicate, sensitive and original. She has a remarkable eye. Highly recommended.

Ballet for Boys and Girls, by Kathrine Sorley Walker and Joan Butler, is an ambitious work and, to the novice, rather confusing. It begins by explaining classroom exercises and the differences between male and female dancing, goes on to discuss La Sylphide, a Romantic ballet, heads back to the court of Louis XIV and jumps forward to Giselle. The text is informative, though not very lively, and gives an all-round, albeit diffuse, picture of the world of ballet. I Can Dance, by Brian Bullard and David Charlsen, with a foreward by Melissa Hayden, contains a wealth of useful information for the older dancer taking class, but is way above the heads of the two children demonstrating their extensions in the cover photograph. It is illustrated with photographs of Bullard and a girl of about 8 years. The text reads like an instruction manual and is more useful to the teacher than to a very young student. As a reference book of basic dance steps, for nonprofessional adults who like to practice at home, it is both solid and illuminating.