Children's nonschool learning provides a foundation for school instruction and problem-solving. Examples of nonschool learning are taken from various cultures. This study examines what young children know about written numerals in their everyday environment, how they come to understand the meaning of written numerals, and how they use this knowledge to reason and interpret nonschool situations. Most of the data are from interviews with the same children in the middle of kindergarten and again at the end of second grade. This is supplemented with test data obtained from the same children when they began kindergarten. Methods and results are discussed. Includes 43 references. (DC)