This article focuses on the use made by Finnish vocational upper secondary students, including their opinions, with regard to the voluntary-based aspects and activities of a compulsory mathematics online course. In particular, the study investigated whether the vocational field affects students’ views and actions. There were altogether 313 students from six vocational fields participating in this study, but the number of students who responded to the feedback questionnaires related to the different opportunities and activities varied. Of the opportunities offered, the repetition opportunity was the most used and the most useful from the students’ point of view. Almost 90% of the respondents ended up, either voluntarily or under guidance, taking advantage of the repetition option. The education video was watched by almost 60% of the students responding to the questions related to the video. Students had a positive attitude towards the effects used in the educational video, the length of the video, and the level of explanation of theory. Approximately half of the respondents who were offered an additional practice opportunity took advantage of this, and the opportunity was seen as quite useful. There were only minor, if any, statistically significant differences between the vocational fields regarding the use of the opportunities offered and the opinions related to them. This research will assist in developing online teaching of mathematics at vocational upper secondary level and will also offer guidelines for the development of online education more generally.