Background:
The aim of this study is to develop a scoring rubric to assess primary school students' problem posing skills. Posing a problem under certain conditions or reorganizing an existing problem requires great cognitive effort and positively affects mathematical development. Problem posing is not only a learning activity. It also improves students' conceptual understanding, enhances their mathematical communication skills, interests them in mathematics and their environment and gives them the opportunity to use creativity.

Material and methods:
A rubric including five dimensions namely solvability, reasonability, mathematical structure, context and language was used. For the purpose of testing the reliability of the developed rubric, selected independent raters scored the participants’ problem posing skills both with and without the developed rubric. Theory of generalizability, which guided the study, led through testing the reliability of the scores.

Results:
More reliable scoring was obtained using the scoring rubric. The G and phi coefficients rose somewhat after increasing the number of items and raters in both scoring methods. However, increasing the number of items affected these coefficients slightly more than increasing the number of the raters.

Conclusions:
Using a scoring rubric increases inter-rater reliability as well as revealing the differences amongst students.