Mike Wood was a young father when his toddler’s struggles to read led him to develop one of a generation’s most fondly remembered toys.

Mr. Wood’s 3-year-old son, Mat, knew the alphabet but couldn’t pronounce the letter sounds. A lawyer in San Francisco, Mr. Wood had a new parent’s anxiety that if his child lagged as a reader, he would forever struggle in life.

So on his own time, Mr. Wood developed the prototype of an electronic toy that played sounds when children squeezed plastic letters. He based the idea on greeting cards that played a tune when opened.

Mr. Wood went on to found LeapFrog Enterprises, which in 1999 introduced the LeapPad, a child’s computer tablet that was a kind of talking book.

The LeapPad was a runaway hit, the best-selling toy of the 2000 holiday season, and LeapFrog became one of the fastest-growing toy companies in history.