Recently there are a few similar Qs posted at RG, here is one:

https://www.researchgate.net/post/What_platforms_would_you_recommend_for_online_classes_that_are_flexible_easy_to_use_and_free_or_inexpensive

I recommend to read the document given by colleague Razan Bassam Nweiran

Most of these are free: https://www.schrockguide.net/online-tools.html

Try ZOOM app for the small groups.

As you specifically asked for a virtual environment I recommend Hubs https://hubs.mozilla.com/

You will be able to have an entire class in the virtual space, you can import 3d objects for students to examine, you can display web cams, youtube videos, PowerPoint slides, etc and you can customize the environment.

This software works on all PC, Mac, Android, iPhone, Oculus, HTC, Steam, WMR platforms (as both a standard app for 2D screens and as a VR app for headsets).

Alternatives discarded for not meeting criteria Zoom, Microsoft Teams

Alternatives discarded due to lesser compatibility AltspaceVR, VRChat

I hope this helps.

Dear Ali Najafi

Khan Academic is a very innovative and up to date virtual learning free environment. I strongly recommend it!

In my humble opinion, Khan Academy is on the cutting edge of virtual learning free technologies!

In my country, as part of real-time e-learning, including Virtual Education Classes, teenagers and students use several applications to communicate with teachers, including zoom installed on laptops or smartphones.

Regards

Dariusz Prokopowicz

Check this out pleaese: ezTalks Webinar

You could use google classroom and make a video lecture using Snagit software.

Google Classroom for teachers is easy to set up and easily used by students. Teachers can have all the information and assignments in the classroom in one place. Students can access their studies or assignments from anywhere, if they have the Internet.

Free Conference Call

Thank you to everyone who responded and guided me.

GOOGLE CLASSROOM and GOOGLE MEET are two nice software/ apps for online and virtual class

Google classroom

we use Google classroom w meet.Google, Zoom, slide shows, google docs (collaborative in real time), cell phone, Face time and creative phone apps

Google Classroom and Zoom are good option.