The logistics and cost of running large class tutorials to improve learning for students in high enrolment courses raise questions about whether the associated effort and cost are worthwhile. The option to replace these class activities with online homework with its promise of built-in feedback is attractive. Using an activity theory lens and an experimental design, we compared the impact of class tutorials with online homework to support learning offered in face-to-face lectures on student performance. We found that there were no topics in the introductory organic chemistry syllabus in which students who had completed online homework instead of large class tutorials performed better. In contrast, for all topics except 'Curved arrows in mechanisms', the mean performance of students who had attended a large class tutorial was statistically significantly better than for those who completed online homework instead. This large quantitative study with a sample of 667 students demonstrated the advantage conferred by face-to-face tutorials with peer learning and personal feedback even in a large class setting with only three sessions per student. Our recommendation is that an online homework system in blended courses should not replace face-to-face tutorials for topics reliant on personalised instruction and feedback. We advocate for investing resources and effort to provide face-to-face problem-solving sessions in high-enrolment introductory organic chemistry courses to improve performance.