In the novel, Wade describes his positive experience with virtual school. Why does Wade think that virtual learning is effective, and do any virtual classrooms exist in our present world?

One of the main reasons Wade enjoys learning is because the virtual school environment neutralizes peer bullying, a substantial challenge in the traditional school environment. As Ludus is a no-PvP zone (the simulation disallows combat activity), students cannot indulge in any form of physical violence. Additionally, all students have the ability to mute harassing comments from other students. As a result, teachers can concentrate on what they do best: educating.
In a virtual school environment, students attend field trips as avatars. They are immersed in a 3D learning environment that effectively makes difficult concepts accessible to them. During a world history class, Wade and his peers are given an expansive survey of Tutankhamun's glorious reign in 1334 BC. They also witness the discovery of his tomb by archaeologists in AD 1922. The virtual field trips reinforce the prestige that surrounded Tutankhamun in life and death.
Meanwhile, in biology class, Wade and his peers enjoy an immersive tour of the inside of a human heart. For art class, students visit the elegant Louvre while ensconced on earth in their haptic chairs. There are indeed virtual classrooms today, the most prominent of which is Meisei Cyber Gakushukoku in Japan, where students attend school as uniquely-designed avatars. To date, teachers have incorporated virtual environments such as OpenSim, Second Life, and even World of Warcraft into their classroom experience.