With the shift to online learning, there has been an increase in a new type of cybersecurity issue called “zoom bombing”; where disruptive “trolls” attack online classes by sharing inappropriate or offensive screens, comments, or annotations, etc.
You can use the new security features (shield button) to manage your participants and their permissions during the class:
Zoom support have compiled a list of techniques for securing your classroom: https://blog.zoom.us/wordpress/2020/03/27/best-practices-for-securing-your-virtual-classroom/