Middle School Students Unlimited, Limit Understanding Of Survey Research

The meaning of infinity as a common vocabulary in our everyday life and an important notion in mathematical fields are quite different, which suggest it's difficult for students to understand some mathematical concepts involving infinity. This study focuses on informal notion of limit and infinity hold by 401 senior school students:1. By investigation and interview, it was found that students understand mainly "" in the lim f(x) as a large number and potential infinity, and the role those understandingsplay in their solutions of limit problems s as lim f(x).2. By investigation and interview students' informal models that invoked in giving meaning to the function limit and sum limit, it was found that the former informal models involves limit an unreachable-. limit as reachable limit as precise value and limit as approximation ,and the latter involves limit as closeness limit as precise value limit as approximation and limit precise value, of these models, limit as closeness and unreachable is most common misunderstanding . These informal models arose and developed depend on informal meanings of technical language and conceptual difficulty of the notion of infinity.On the basis of findings mentioned above, some advice are given on limit teaching, it is advisable for teachers to pay attention to appropriate expression of infinity. Finally the limitations of this paper and further study about this topic are pointed out.