How Classroom Video Conferencing Works

At its most basic level, video conferencing in education connects remote students to teachers. On a more exciting level, it also leads students on virtual tours, brings far-away experts on camera for interviews and allows kids to try out their fledgling foreign language skills on their peers from other countries. While such activities might have been difficult in the past due to travel costs, time constraints and inconvenience, classroom video conferencing can offer a work-around solution. Video conferencing lessons for schools can also ignite an interest and enthusiasm for learning that traditional teaching methods sometimes can't.

For instance, how often did your middle-school science class interact with astronauts at NASA? Yet students from California were able to take a close-up tour of a NASA facility with their school's video conferencing equipment. As part of their science and engineering project about self-sufficient living spaces, the students toured a space station training facility where they got a close look at all the equipment and were able to ask their guides questions [source: AT&T]. Such a field trip would have been impossible without video conferencing because of the distance and time involved.

Even the best students sometimes hit a wall with traditional teaching methods. Sometimes it just helps to put a face with whatever you're learning. After completing a unit on the Sun, Earth and Moon, students in England got to do just that, interviewing a scientist from the London Science Museum. Their excitement about the interview opportunity motivated them to come up with good questions, and they were so pleased with the whole experience that they asked to present to the rest of the school what they had learned [source: Global Leap Study 31].

Students from Monkseaton Language College in England were equally excited when they got the chance to practice their language skills with students from a classroom in France. Learning a language by making flash cards and filling out worksheets is one thing, but speaking it with native speakers is another [source: Global Leap Study 15].

Of course, not all classroom video conferencing experiences are positive. The technology sometimes presents obstacles. If users aren't familiar with how to deal with such issues, the benefits of video conferencing education can be lost. Learn about the technology of video conferencing and some of its downfalls on the next page.

To gain a better understanding of video conferencing, it helps to learn exactly how audio and video signals captured in a classroom arrive at their destination. Beyond the obvious necessities of a camera and monitor, an audio system with microphone and speakers, and a control to place the call and adjust things like volume, you also need a device called a codec. The codec is the name of the piece of equipment that formats the audio and video signals for transmission. Its need will soon become apparent.

Successful classroom video conferencing relies on both the audio and video information being transferred in real time. These two streams of information take up a lot of room, which standard communication wires like phone lines can't handle. In order for the data to fit in the standard wires, it has to be converted into a smaller format so that it can be transported easily and efficiently. It's the codec's job to code the analog audio and video recorded with the microphone and camera into a digital format.

The information is broken down into smaller packets and then delivered to the receiving end by one of several possible methods such as cables, regular phone lines or an IP-enabled network. The codec on the receiving end then translates the digital signal back into an analog signal for display on the monitor.

Depending on the quality of the equipment involved, the reproduced signals may arrive in tip-top shape, or they may be degraded in the translation process. Lowered quality can occur because of how compression is achieved: by taking out little bits of information. Think of it as crumpling up a drawing so you can toss it across the room. Crumpling it into a ball allows you to get it there more quickly than trying to simply float it, but when you smooth out the paper, the picture will be somewhat distorted. The same thing often happens with video conferences, which leads us to some of its drawbacks.

Pixilation results from the codec having to deal with the rapid flow of information. To manage the load, the codec reduces the number of video images displayed per second, which makes movement look jerky. The codec also decreases the resolution of the photos, which takes out detail and makes images look fuzzy, like the man's face in the picture.

Audio delays happen when the codec can't keep up with the rate of transmitted sounds. By the time the sound gets compressed, transmitted and decompressed, th­e person is often finished talking, and awkward time delays occur. When this happens, you may notice that people's lips do not match up with what they're saying, which can be distracting.

Echoing might happen if your audio system isn't set up properly. Background noise can contribute to this problem, but it's usually easy to fix by resetting the echo canceler if there is one, moving microphones or using headsets and external speakers.

If users are new to the technology, the effects of data compression can make communication difficult and override the potential benefits of video conferencing lessons for schools. But with practice, teachers can easily overcome the obstacles. Other aspects of video conferencing, though, can affect the quality as well. Learn more about the different video conferencing setups available and the two most common transmission mediums on the next page.

The biggest difference among video conferencing systems is how the signals are transmitted. The particular method can have a big impact on the connection options, as well as the quality, speed and cost of the transmission. Most systems today are based on standards, so that systems using different equipment but the same standard can connect without special equipment. Two of the most common standards are H.320 (ISDN) and H.323 (IP). Other standards also exist, such as T.120, which enables data sharing, and H.243, which enables multipoint conferencing, or communication among more than two locations.

ISDN- (integrated services digital network-) based systems use existing phone lines t­o transmit data, whereas IP- (Internet protocol-) based systems use Internet networks. Many schools seem to like ISDN because it establishes a dedicated link unaffected by other users. This makes the quality of an ISDN connection predictable. The drawbacks to ISDN are that it isn't always available in rural areas and that it racks up per-minute long-distance charges. To connect with other users, people using ISDN-based systems simply dial the number of who they want to connect with, like a regular phone call.

IP-based videoconferencing, on the other hand, costs less, especially as network connections become more prevalent. Since it uses the Internet infrastructure, and many schools already have existing networks, using an IP network doesn't require setting up any special connections. However, depending on the network's capacity, signal transmissions can be slow and unreliable. If many other people are using the network, the quality of the video conference may be negatively affected. With the introduction of broadband and other improved Internet technologies, though, IP-based video conferencing is gaining in popularity.

Aside from the different standards used to connect, the physical arrangement of classroom video conferencing equipment also varies. Some schools have rooms dedicated to the technology, while others have portable systems or even desktop units.

Teaching methods have come a long way since the days of the blackboard and one-room schoolhouse. If you want to learn even more about video conferencing lessons for schools, follow the links on the subsequent page.­