This study explores how the use of learning analytics (LA) visualizations to eliciting examples tasks (EET) on the topic of functions can shape middle school mathematics teachers' formative assessment (FA) practices. Teachers' practices were examined when provided with LA visualizations, offering them an interactive analysis of their students' work. The findings showed that LA visualizations enhanced teachers' evaluations of their students' work, including challenges and strengths. Two key areas of FA were supported when teachers interacted with LA: designing and implementing classroom discussions and other learning activities and enhancing the quality of feedback. The patterns of use indicated that when teachers were not convinced of the data presented, they used critical thinking and accessed other reports and interactive tools to confirm their impressions.