01 - Students complain they can't see the bottom of the projected image
02 - Brand-new screen doesn't perform as we expected
03 - How do I start to use web materials in my classes
04 - Kids are having trouble hearing class discussions
05 - Trouble making legible transparencies on the copy machine
06 - Plasma Display Panels or video projectors?
01.All of the classrooms in our high school have the projection screens hung from the sliding hooks at the top of our chalkboards and some of the kids half-way back can't see the writing near the bottom of the screen because they are seated in rows directly behind one another.
I hate to ask the maintenance guy to do much because he's swamped most of the time. Is there any way I can get the image higher by mounting the screen from the ceiling… safely but easily?
Answer: If your classroom ceiling is of the "T Bar" type, where metal bars run both ways across the ceiling to support ceiling tile, just buy a couple T-bar scissor clips that are made to attach projection screens to ceilings. They are easy to install and are available from the DA-LITE screen company. There is a picture of the clips on their web page at
After your maintenance guy sees how easy they are to install, I don't think he'll feel imposed on.
04. I recently discovered that some of my elementary kids are having trouble hearing the class discussion in my room. I've talked with the maintenance people and they've listened to the noise from the cooling/heater under my classroom windows but said it didn't sound too loud to them and suggested I talk louder. I explained that the kids can hear me… they can't always hear when one of the kids is reading or making a point. They don't seem to think I have a legitimate concern. They say to just have the kids speak up! What can I do when certain kids just don't have strong voices?
Answer: You're not alone in your concern about this problem. Across the land, architects and engineers have bent to the wishes of school boards and building committees to keep construction costs down.
One standard way of doing this has been to install the heating and cooling fan right in the classroom so that large air ducts don't have to be run from a remote fan room. This usually takes the form of a cabinet installed under the classroom windows.
As with the room units in hotels and motels, it saves money, but it has created such a hearing problem that a national panel of over 50 architects, educators, acoustical consultants and audiologists made a recommendation that classroom noise be controlled under the Americans with Disabilities Act (ADA) along with all the other problems that keep certain kids from having access to learning.
A study done in the early nineties showed that over half of all teachers surveyed said that their students have trouble hearing because of noise in the classroom.
One approach, advocated by manufacturers of electronic audio equipment, is to equip the teacher with a microphone and wireless transmitter, and the most hearing impaired kids with wireless receivers and headphones. For the kids who need to speak to other kids, they advocate a floor mic. If the problem is only to let a few kids hear the teacher, there is a case for this approach.
It has serious limitations though. Even kids with perfect hearing, particularly in the lower grades, don't have the experience to mentally fill in missing parts of words as adults do. And for children learning a second language, the odds are daunting!
Essentially, each kid would have to be equipped with a receiver and headphones, and each kid would have to go to the floor mic to say anything. Talk about inhibiting!
The only logical approach is to reduce the heating/cooling fan noise in the classroom to an acoustical standard that is called "NC30." This measurement can be made by acoustical consultants using commercially available acoustic measuring devices.
If the NC30 noise level should someday become an ADA standard, lots of parents will have the opportunity to sue the school systems that do not conform, in the same way they can now sue to get wheelchair ramps, drinking fountains at the right height, and wheelchair restroom stalls.
Since you are obviously concerned about the effect on the children, begin to educate anyone who will listen . It isn't mandatory now, but I personally think it's only a matter of time!
05. I use an overhead with transparencies that I've made by copying selected text
from magazine articles. Some of the kids in my high school classes complain that they can't read the text on the
projection screen from the back of the room. I first assumed that they just needed glasses, until I stood at the
back and couldn't read the text myself because it was just too small. I tried moving the projector away from the
screen; the text got bigger, but now it spills over the edges of the screen onto the dark chalkboard and can't
be read either. The AV people say to put less of the article on the screen at one time, but I can't see how to
do that without re-typing the article. Am I missing something?
Answer: A rule of thumb to follow for legibility is to make a sample of various heights of text, then actually project the text on the screen and measure the height of the characters.
Here's what to expect:
¼ inch high lower-case characters on the screen can be clearly seen by people with good vision no more than 8ft. away.
3/8 inch high lower-case characters: no more than 12ft.
½ inch l-c: 16ft.
5/8 inch l-c: 20ft.
¾ inch l-c: 24ft.
7/8 inch l-c: 28ft.
1 inch l-c: 32ft.
2 inch l-c: 64ft.
4 inch l-c: 128ft.
You may be shocked to see how little information can really be put on a transparency, using these guidelines, but test them for yourself. After a while, you'll find that you do much more "outlining" in your own words, rather than making copy machine transparencies of pre-printed text. It is worth the extra time. You will still want to include any original pictures and illustrations, however, by copying them onto transparencies.
06 I'm a college instructor who uses a lot of video projection in my classes. One of the problems I have, however, is that the video projector requires the lights to be low - and since my class is right after lunch - a lot of kids fall asleep in the dim light. I'm seeing more and more of the flat screen TVs in stores, now, and I wonder if I could use one in my classroom... since they seem to work well in normal room light.
Answer: Sure, if your classroom is small. The main problem with the "plasma display panels" (PDPs) as they're called, is their limited size. The lower-priced PDPs are only about 42 inches on the diagonal.
If your video materials contain much text or many graphs with text on them, you'll want to experiment by drawing a rectangle on the chalkboard 9 units high by 16 units wide having a diagonal of 42 inches. That is the actual size of the PDP. (Manufactured for the next advance in video, HDTV.) Next, make another box inside the first one which is 3 unit high by 4 units wide. (The proportions you have beeen used to with your video projector.)
Finally, carefully hand print some text in the 3:4 rectangle using the guidelines in faq #5, above, considering the length of your classroom. This little test will tell you just how much text you'll be able to put on the PDP at one time.
By the way, not all PDPs are able to handle text well. Check out the range of PDPs available at any number of web sites (Panasonic, Hitachi, Sony, Pioneer, etc). Or, visit one popular site which gives information on four different manufacturers: http://www.electrograph.com/default.asp?swf=done. Note that all the prices are a little salty yet.