In this preliminary study, to inform a larger study where Year 8 students create an online module for peers, I surveyed mathematics teachers (n = 30) on essential mathematics topics: (a) most critical for students' success, (b) most conceptually challenging for students, and (c) in which more fluency is needed, as well as (d) their likelihood of considering an online course as an intervention. Fractions concepts, times tables, and equation solving were most critical for success; students need more understanding of fractions concepts, and more fluency in both fractions concepts and times tables. Online course use addressed teachers' concerns for students in essential mathematics topics.