A secondary data analysis was conducted using a large dataset from a study related to online professional development for eighth grade teachers of mathematics. Using this data, the paper provides a snapshot of the current state of teachers' knowledge related to proportional reasoning and functions. The paper also considers how teachers' knowledge is related to student knowledge in these two areas. The analysis shows that teachers' knowledge was deficient for several items. Further, students whose teachers had lower levels of knowledge showed statistically significantly lower performance in functions. (Contains 5 tables, 2 figures and 2 footnotes.)