In object-oriented programming, a virtual class is a nested inner class whose functions and member variables can be overridden and redefined by sub classes of the outer class. Virtual classes are analogous to virtual functions.

The run time type of a virtual class depends on the run time type of an object of the outer class. (Just like the run time type of an object decides which virtual function should be used.)

A run time instance type of the outer class object not only decides on the polymorphic type of its own type object, but also on a whole family tree of virtual class members.

Purpose

Virtual classes solve the extensibility problem of extending data abstraction with new functions and representations. Like virtual functions, virtual classes follow the same rules of definition, overriding, and reference.

When a derived class inherits from a base class, it must define or override the virtual inner classes it inherited from the base class. An object of the child class may be referred to by a reference or pointer of the parent class type or the child class type. When the reference or pointer invoke the virtual inner classes, the derived class’s implementation will be called if the object is of the derived class type. The type of the outer class determines the run time of the inner virtual class.

A method with an object argument has access to the object’s virtual classes. The method can use the virtual classes of its arguments to create instances and declare variables. Virtual classes of different instances are not compatible.
Below are some of the key components of a virtual classroom. I am sure that this could be expanded upon further, but for the sake of simplicity I have only included what I believe are the most defining ones.

Definition
A virtual classroom is an online classroom that allows participants to communicate with one another, view presentations or videos, interact with other participants, and engage with resources in work groups.

Non-Restricting
A virtual classroom allows both learners and instructors around the world to participate in live classes to collaborate and interact. MOOC programs like Coursera are a great example of this concept in action.

Affordable
The low costs of virtual classrooms are considered to be a major advantage. Learners can save money by not having to worry about travel expenses. Participants also save time since all that is needed is an internet connection.

Flexible Learning
Online classes also allow for the ability to record class as it happens, including any presentation audio and visuals. This means that the content is accessible even after being delivered, an added benefit for those who want a quick refresher, or perhaps did not fully understand the first time.

Practical and Proven
Synchronous learning is a learning environment where everyone takes part in the learning at the same time. A traditional lecture is an example of this type of learning, and has been used for hundreds of years. Online learning enables this same type of experience, but with far more conveniences and tools.

Accessible
Virtual classrooms can be used to deliver lectures, or even tutorials online. They are also great options for impromptu meetings and group projects where members need to check-in on progress and bounce ideas of one-another. With the virtual environment, ideas and collaborators are never far away.

Objectives

Accessories

Features of VCR

Advantages

Activities in virtual class room

References

http://iiti.ac.in/docs/downloads/VCR/About-IITI-VCR.pdf

Assignment

1. Write a proposal for creating virtual classroom in your campus
2. Differentiate the learning environment between natural class room and virtual classroom.