Dear Squeak and Blat,
I have a computer in my classroom but I haven't figured out how to use it so that my whole class can see the screen. How can I get this to work for me?
Well M.M., how about just putting the screen up high and giving all your kids binoculars? Seriously, there are a few options--some cheap, some more expensive. One cheap way is to hook the video output from your computer to a TV monitor. Most AV stores will sell an adapter that will transform the signal of your computer to match the video requirements of your TV. Some computers might even have an option to do this built right in! This might work fine for images that are not too finely defined, but don't expect great resolution on the TV screen.
A more expensive but much better option might be to purchase an LCD ("liquid crystal display") plate that accepts the video signal from your computer. This plate goes on top of a bright overhead projector and the plate and the projector work together to display the computer image up on the screen. These plates range in price from one to several thousand dollars depending on how fancy you want to get. Maybe your school can buy one of these and it can be shared by many teachers!
Check out some of the projector companies on the World Wide Web like InFocus, Proxima, and nView. The LCD plate shown here is from nView and the projector is from InFocus.
Ms. Metronome, Blat's on the right track here with his advice but I'd add a few words of caution and additional ideas. If you use the TV monitor approach, you'd better get a big screen TV. Just make sure your kids don't find out how to connect it to cable TV or they'll turn your classroom into M and M's Sports Bar! Don't discredit this option, however, since you can get a 30 inch or large TV for under $1000 at your closest electronics store.
When Blat said to get a "bright" overhead, he means really bright! You need one especially made for computer projection, with lots of lumens (that's the term they use to measure the brightness). You also want an LCD plate that is color and is "active matrix" which means that it can keep up with motion video on the computer screen.
There are also newer versions of computer projectors where the LCD display and the projector are built into one handy unit that is convenient to carry around. They usually call these "multimedia projectors." You also want to buy your projector with the right cables to display from both a Mac and a PC.
Now, Blat said that these cost "several thousand dollars." Let's get more precise here Blat. How about a minimum of $4000 dollars for color! Now you see why a large TV screen can be an alternative when money is tight. However, these projectors fall under the "audio-visual" category so you may be able to make the purchase through funds for AV equipment instead of computer equipment.