Bill Martin Jr., 88, who wrote more than 300 books for children including such classics as "Brown Bear, Brown Bear, What Do You See?" and "Chicka, Chicka, Boom, Boom" that delighted young readers with adventuresome stories told in rhythmic language, died Aug. 11 at his home in Commerce, Tex. He had Parkinson's disease.

A struggling reader until he reached college, Dr. Martin finally learned the skill by memorizing poems by Robert Frost and Walt Whitman that his professor read in class. Once he had learned the verses by heart, he could pick out the words on the printed page.

He remembered his own learning experience when he started to write books for preschoolers. His frequent repetition of words and phrases was intended to help them remember new terms.

"Children will only read when they have language inside of themselves," Dr. Martin told Northwestern University's alumni magazine this year.

After his slow start, he received a doctorate in early childhood education at Northwestern and went on to develop several innovative reading programs as the editor in chief of the school division of publisher Holt, Rinehart & Winston through the 1960s.

He pioneered a participatory approach to learning, with stories that encouraged children to answer questions raised in books. He was one of the first children's authors to tour schools and bookstores, promoting his books by reading aloud to children, often accompanied by music and dancing.

Dr. Martin often made animals his main characters -- "fluting" flamingos and "braying" zebras -- which he described with words that a child might not recognize at first but could begin to understand by listening.

He wrote two of his best-known books, "Brown Bear" and "Chika Chicka," on his own, but he also liked to collaborate with a writing partner, talking the story through as the first step.

He was a native of Hiawatha, Kan., and a graduate of Emporia State University in Kansas. He taught high school drama until the start of World War II and then served in the Army Air Forces for four years.

He wrote his first children's book for his brother Bernard, an artist, who asked him to create a story he could illustrate. The brothers published "The Little Squeegy Bug" (1945), about a bug that turns into a firefly, under their own Tell Well imprint. Former first lady Eleanor Roosevelt praised the book in her syndicated newspaper column, "My Day," and it eventually sold 1 million copies. The Martins went on to publish 10 more books together.

Dr. Martin's marriage to Betty Jean Bachmann Martin ended in divorce. A son died in 1963.

Survivors include a daughter and two brothers.