The jigsaw puzzle has come a long way since its invention over two centuries ago by a London mapmaker. These first puzzles, called dissected maps, were designed to help children learn geography.

Current puzzles offer almost unlimited choices for "kids" from 2 to 102, but this was not always the case, according to researchers at Random House Inc., which makes still-popular puzzles today for children and adults.In the l760s, printer John Spilsbury produced map puzzles with large pieces that slid together instead of interlocking like modern jigsaws. They were priced at $5, so only the wealthy could afford puzzles until the 19th century, when technological advances brought them within the reach of the middle classes.

Then, the range of titles broadened to include topics such as "Chronological Tables of English History for the Instruction of Youth" and "Lessons for Young and Old on Industry, Temperance and Frugality."

Puzzles reached America at the time of the Revolutionary War. However, they did not truly come into their own until the Great Depression of this century, when millions of American searched for inexpensive entertainment.

Puzzles today feature a wealth of themes, shapes, sizes and subjects, all reproduced with brilliant graphics on precision-cut pieces. Children's puzzles may depict favorite characters from books and movies, and can be printed on extra-large pieces designed especially for young children's hands.

Although today's jigsaw puzzles are more sophisticated than the earlier creations, they continue to be excellent teaching tools, experts agree.

Playthings magazine, the toy industry bible, reports that "parents seem to be latching onto puzzles these days in hopes that their children will develop earlier. They're discovering that children are capable of learning much more than anyone thought, at a younger age, and puzzles are a great tool for this."

"Puzzles encourage the imagination and help kids learn, adds Suzanne Glazer of Random House. "Perhaps that's why they continue to be a favorite. They teach problem solving, lead to a sense of accomplishment, and help children increase manual dexterity.

"It's important to select the right puzzle for a child's age and development," she points out. "For very young children, for example, choose inlaid puzzles with no more than 12 large pieces that fit into framework. These are designed for easy manipulation by young hands.

"For older children, ages 5 and up, boxed puzzles are available with up to 100 pieces. For teenagers and adults, the most popular puzzles have 500, 1,000 or even 1,500 pieces that form intricate patterns . . ."