This is an example of dramatic irony
Assure could mean making sure something happens, to comfort or remove doubts from a person, or make someone sure of something.
If it's one word answers it could be persuading, guaranteeing, promising, convincing, reassure, satisfy, or tell.
I hope this helps without answer choices it's kind of hard to know what kind of answer you need. Have a great day!
If it was mandatory they would be given a perfect opportunity for those who love to participate in activities like students who don't know where to start, and those who would like to try with there friends