The purpose of this paper is to explore teachers' ability to explain student reasoning in linear and non-linear patterns and in different types of generalization tasks. A questionnaire consisting of student responses to different types of generalization tasks was developed and then given to a sample of 91 in-service mathematics teachers from 20 schools in Lebanon. Analysis of data shows that teachers' explanations exhibited variations in the extent to which they identified the elements and relationships found in students' responses. The results showed that teachers' ability to explain students' reasoning of linear tasks seemed to be higher than that of non-linear patterns. The findings also showed that teachers' explanations of students' reasoning for far generalization tasks exhibited a larger amount of data (elements and relationships) compared to the explanations for near generalization tasks. [For the complete proceedings, see ED597799.]