George Lucas Educational Foundation
Subscribe to RSS

Size Matters: Large-Screen Digital Projectors

Jim Moulton

Technology Integration and Project-Based Learning Consultant
  • Facebook
  • Twitter
  • Pinterest
  • Share

In Edutopia video segments, you often see teachers and students using a television in place of a computer monitor to provide better access to visual information. The reasons for using the television instead of the monitor are pretty straightforward: The television has a larger screen, and it can be placed higher so that there are no "bad seats."

Though the use of a television is one way to improve the view for your students, it is not enough, and there are other ways that provide even greater access to all. Let's take a look at large-screen projection.

Why Is a Big-Screen View So Important?

Put yourself in your students' place. Imagine going to a professional-development session where the presenter is sharing a Web-based resource that would meet a critical need in your classroom. You are really interested, and hungry for the knowledge. But the only screen available is the presenter's laptop, and though it has a nice 15-inch or even 17-inch screen, there are twenty-four other participants in the room, and you happen to be sitting toward the back. That means that as everyone leans toward the screen in order to see this great utility, your view is blocked completely.

The presenter could regain order, and establish equity, by turning the screen away from the audience and using words to describe what he wants you all to see, but that would leave everyone frustrated. Perhaps he could stop presenting and give everyone time to file past the screen in order to see and try out the Web site, but that would cause too much commotion and seriously interrupt the pace of his delivery. Or, if he was better prepared, he could pass out printed screen shots of what you would have seen if you could view the Web resource live.

None of these solutions is optimal, and, truth be told, chances are that he would carry on, knowing that only a few will really see and experience what was intended as information for all. And those few will be limited to folks who are either lucky enough to be sitting front and center or aggressive enough to force their way into a position where they can see. Probably this is not what you want to see happening in your classroom when a school from far, far away responds to one of your postings, and you want everyone to share in the excitement and to get the same information.

So, How Big Is Big?

The television screens teachers use in the Edutopia video segments are certainly larger than those of traditional computer monitors, and their placement makes them more visible. But imagine there was a television screen -- say, one that was 32 inches (measured diagonally) -- in that professional-development session. That's not a bad size, but the screen measures 20 inches by 25 inches or so. That's still not a great improvement for someone who isn't sitting near the front. Sure, if it's placed high enough, everyone will get a sense of the information, but will they gain deep understanding and truly be effectively engaged? Probably not.

If a TV Won't Cut It, What Is the Solution?

A digital projector. These devices allow you to feed a computer's signal in and project it onto any screen-like space in the classroom. If you have a real screen, great! Use it. Don't have one? Clear off a wall, tape newsprint to it, and -- presto! -- you have a screen now! And a decent digital projector can fill a screen as large as any wall in your classroom with a bright, clear image, making it possible for everyone to participate in a Web-based project or another utilization of digital resources. But there are a few things one needs to know about digital projectors.

How Bright Is Bright?

Lumens are. Every projector will promise to deliver a specific number of lumens, a measure of brightness. For regular classroom use, with the lights on, plan on looking at projectors with a lumens rating of at least 1,000, preferably higher. If you are offered a free one as a local business upgrades to a new projector, don't turn down the gift of an 800- or 900-lumen projector, but if you are shopping for a new one, the brighter the better. The difference can be remarkable! It has to be useable when the lights are on, though. Remember what happened in the classroom when you were a kid, and the teacher turned the lights off to show a film or a video? It turned into naptime for me more than once.

Most bulbs for digital projectors are $150-$300 -- not surprising, given the amount of light they need to produce to create the images they do. Therefore, it is important to pay attention to the anticipated bulb life. Look for a projector that offers 1,500 or 2,000 hours. At that rate, a projector used four hours per day, five days a week (an aggressive estimate, of course) will last 300-400 days -- up to more than two school years. And don't worry too much about the facts of daily in-school use, as most current projectors are portable and made for the road. As long as you take reasonable care of the projector, the bulb will provide good service.

LCD, or DPL?

LCD (liquid crystal display) projectors have three separate LCD panels -- one each for red, green, and blue components of colors -- that work together to create the image. DLP (digital light processing), a proprietary technology produced by Texas Instruments, has a single light-processing chip covered by thousands of tiny mirrors that move to control the light reflected out into the image. Because of their technical differences, DLP projectors, with their single light chip, can be smaller, while LCD projectors tend to create a slightly sharper image in side-by-side comparisons.

Because they are competing technologies, don't expect these differences to remain stagnant. When shopping for a projector for your classroom or school, be sure to look carefully at both kinds. A good question for your vendor might be, "I am a teacher, and so this projector needs to be rugged, portable, bright, and sharp. Would you recommend that I look more closely at DLP or LCD projectors, and why?" Listen to what they have to say, and then make your own decision. To read more about the differences, search the phrase "dlp versus lcd" online.

What About Resolution?

VGA? SVGA? XGA? Arrrgghhh! Acronyms can drive folks up the wall, but you really do need to pay attention to this. Resolution, in simplest terms, defines how clear the image your projector projects will be. The letters refer to different resolutions, or how many pixels (the small elements that comprise an image), your image will be made up of. The more pixels, the clearer the image. The common resolutions with a 4:3 ratio are SVGA (800 x 600 pixels) and XGA (1024 x 768 pixels).

Be aware that some applications, most notably Apple's iMovie, require XGA as a minimum video resolution. If you are going to use your projector to show movies your kids have created on iMovie, you'll need either XGA or an SVGA projector that can be pushed up to "pretend" it is XGA. Again, more questions for your vendor! Just remember: the higher the resolution, the better the image.

It's All About Being Connected

A projector by itself is really just an intensely bright flashlight. But even beyond the classroom computer, there are lots of things that can use the projector's power to make themselves large! Because of this, you want to pay attention to what kinds of devices can be connected to any projector you are considering.

Though the vast majority of current projectors connect to computers with the traditional monitor cable, some of the newest projectors may feature DVI (digital video interface) connectors, lots of flat blades instead of pins, requiring an adaptor to connect to a traditional VGA (video graphic array) monitor cable. Some projectors allow you to connect two computers at once, and toggle back and forth between them, while others provide wireless connections to your computer.

And don't forget good old RCA plugs, the red, white, and yellow ones we have all wrestled with behind the VCR. These will allow you to easily connect your VCR or DVD player to the projector, while a USB connector can allow you to connect a digital camera so that you can run a slide show of images through the projector directly off the camera.

This is the first of two blog posts on digital video projectors. Read the second post.

Was this useful?

Jim Moulton

Technology Integration and Project-Based Learning Consultant

Comments (6) Sign in or register to comment Follow Subscribe to comments via RSS

Peggy Benton's picture
Anonymous (not verified)

This comprehensive post on projectors is really helpful. Most teachers only have one or two computers in a class and need to project a video or their one copy of a program to the class. Unfortunately many schools only have one projector, so actual use in the classroom is pretty infrequent. Some teachers are adding smart boards or white boards as well so they can write on the screen. I have recently seen a number of devices for students called "audience response technology" which allow each student to hold a unit the size of an ipod and click on answers during a presentation or test. I wonder if anyone is using these units when they teach and can comment on their usefulness.

Anita Harris's picture
Anonymous (not verified)

A laptop or computer plugged into a larger screen tv helps a lot. I prefer the Smart Boards. With them at least you are able to have all students view what you are projecting without the worry of no one being able to see it. It also provides you with tools to assess what you are teaching by taking a snapshot of key points and later printing to pass out to your students. As far as the "audience response technology" devices mentioned above, these are handheld interactive devices that provide students more hands-on. The ones we are using are made by Quizdom and are very easy to use. Also, there are various learning games on the system that directly correlates to the standards of your state. That way the students are actively engaged using something that interests them and learning at the same time. Teachers need to remember to use these handheld interactive devices throughtout the year for retention of knowledge purposes and not wait until testing time at the end of the year.

Susannah Finley's picture
Anonymous (not verified)

In response to Peggy's comment on "audience response technology":

The University of Tennessee has completed a pilot study on "personal response systems".

Clicker Technology at UT Knoxville
An excerpt from the site:
"In the Fall of 2005, UT Knoxville's Office of Information Technology (OIT) conducted a Pilot Study on the use of personal response systems, called 'clickers,' in the classroom. The study was conducted with eInstruction's CPSrf system...

Clicker technology use varied among faculty from taking attendance at the beginning of class, to asking recall, processing, or application questions, to polling student opinions on controversial issues...

Preliminary student survey data indicates an overall satisfaction with the use of clickers in the classroom. All but one (1) of the clicker pilot faculty plan to continue using clickers in the spring, including implementing more interactive strategies."

Jeff Jewett's picture
Anonymous (not verified)

Our school's social studies department is fortunate in that it has access to both the Smart Board and "audience response technology". The Smart Board has been a tremendous addition to the presentation of our lessons as it allows Powerpoints to come "alive" and can be utilized for so many uses. The "audience response technology" we use is the system developed by eInstruction and is called the Classroom Performance System (CPS). I used CPS during the past year and was amazed at all the advantages. I used in my AP class as well as my academically challenged class.

The major pluses included:

1) Allowed feedback from every student simultaneously while being totally anonymous. Students that were shy or worried about embarrassing themselves could participate freely.

2) Became a new method to administer quick check-up or reading assignment quizzes. The best part of the system allows item analysis instantly. Students didn't have to wait until the next day to get their quizzes back and teachers could see immediately which concepts the students were grasping and which ones needed more work.

3) Also has two review game options which my students went "nuts" over.

Highly recommend looking into such systems. They are a tad expensive but well worth it provided one looks into all the features available.

Jim Moulton's picture
Anonymous (not verified)

"Audience Response Technology?" So I am to read this as "students as audience?" Is this not a reinforcement of the "sage on the stage" educators have been trying to move away from in order to support the development of critical 21st century skills? Okay... Sure... I have been known to say that "teaching is theater," but I guess I had a more improvisational theater in mind.

When I think about technology in the classroom I hope for a more robust, more active, and more level playing field, where teachers and students "meet in the middle as learners..."

So help me understand.

Please extend these stories to show that the use of these tools (which to me feel troublingly close to our current reality show insistence on "making our vote count NOW") is embedded in a truly interactive, rich learning experience. It may be PBL, service learning, community connected, or otherwise, but please provide the bigger picture and the role this tool plays in that bigger picture.

I am hoping that they are being used as a way to efficiently, quickly, and surely "get hold of factual content" so that the class can move on to doing something important, real, and purposeful with that knowledge.

As Paul Harvey would say, it's time to hear, "The rest of the story..."

*And as a sidebar, I would suggest we begin using the term "interactive whiteboard" as opposed to "smart board." Smart Technologies is one of a growing number of companies that produce this type of tool, and each has software with different capabilities. Beware in the age of open source the acceptance of a single source... ;-}

cheap computers's picture
Anonymous (not verified)

I think that's not a bad size, but the screen measures 20 inches by 25 inches or so. That's still not a great improvement for someone who isn't sitting near the front.

Sign in to comment. Not a member? Register.