The theoretical framework in the thesis is a combination of Anna Sfard’s theory of reification and Heinz Steinbring’s epistemological triangle. The empirical part of the study is based on my mathematics course from the C to B level in the Danish secondary school and contains 13 assignments distributed during the course and reach a total of 232 task. The main result from the thesis is that communication is the key ingredient to encourage a reification. It is only through communication that students get the opportunity to address processes and mathematical entities as objects. Furthermore, it seems as if the functions are relatively easy to objectify, but mostly when a specific function is presented. Tasks involving other representations contradict a reification of functions. When other (or more) representations are used, such as translate text into mathematical signs or graphical representation it is harder to detect the structural understanding in the answers. This might explain the result that differentiability never is fully objectified.