There are lots of really fantastic platforms for online meetings but free versions they offer can be quite limited. You can by-pass the price of Adobe Connect (one of the best) by signing up for a 90-day trial period.
Other options:
Microsoft Teams free, very user-friendly, offers a number of features – chats, video meetings, sending files, screen sharing, online voting etc. Watch a short tutorial
Zoom– free but a video meeting is limited to 40 minutes; offers lots of features.
Both offer screen-sharing option which is super fab as you can present whatever you want to your student/students or vice-versa.
Finally, the one I use – Google Meets which evolved of Google Hangouts. Watch the Jamie’s tutorial here.