It was 1990, and Michael Wood was feeling frustrated. His three-year-old son was having trouble associating letters with their sounds. Why couldn't someone invent a toy to help toddlers learn those phonic connections? The Orinda lawyer did just that, and founded LeapFrog in 1995 to market the result. Wood now sits at the helm of the hottest educational toymaker on the planet. The Emeryville company's main product, LeapPad, was the industry's top-grossing toy last year, besting Hot Wheels, Barbie, and Pokémon. The electronic device accepts LeapPad books -- themselves the third top-selling toy category last year. Using a special pen, preschoolers can point at letters, numbers, and words to hear how they're spoken, play learning games, and read stories with the pad's help. The success of Wood's enterprise, which joined forces with Knowledge Universe in 1997, is particularly impressive given the toy industry's recent lackluster performance. "They were the only toy company in the top 100 that had double-digit growth in the first half of 2001, then they did it again in the second half," says Reyne Rice, a spokeswoman for NPDFunworld, which tracks toy sales. Rice says LeapFrog, which now has more than fifty products, scored five of the ten best-selling items in the preschool segment last year, and eight of the top ten in the "preschool electronic learning" niche. With its new offerings geared toward older kids, toy industry followers expect LeapFrog to continue hopping up the revenue charts.