Chinese researchers investigated how mathematics teachers in two elementary schools in northeast China adapted the national curriculum. One school was in a very poor, mountainous area, and the other school was in a very large city. Both used the national curriculum and the same set of teaching materials. Researchers used ethnographic methods to collect data. Over 4 weeks, they conducted formal and informal interviews with teachers and principals, chatted with students, observed lessons, collected in-house curriculum documents (e.g., lesson plans and work schemes), and attended staff meetings and subject panel meetings. Results indicated that teachers in both areas closely followed the requirements of the textbooks and suggestions of the teacher reference book. Teachers had a strong influence on how the subject was planned and delivered. Their decisions were based on professional knowledge, educational beliefs, and the public examination. There were some marked differences between urban and rural schools in the way teachers adapted the curriculum and teaching materials. There were obvious differences in terms of school culture between the two areas. Teacher development was crucial to successful curriculum change. (Contains 11 references.) (SM)