Three Little Letters Make a Lot of Difference

All files have a format with special coding that let's a software application know how to handle and interpret it. File formats are identified by a file extension at the end of the file name, such as ".jpg" for a particular type of graphic file. It's important that you understand this concept because different file formats are used in different ways. (Note: In newer versions of Windows, file extensions are not always shown unless you tell the system to do so, although the system does use icons to indicate different file formats. Check your Windows manual to see how to display file extensions.)

Some file formats are called "proprietary," meaning that they refer to a specific file used by a program for a specific manufacturer. For example, ".doc" is a proprietary extension used to identify Microsoft Word files, and ".psd" is used by PhotoShop to identify files it creates. These default extensions are assigned to files you create in those programs.

There are also "open" or "standards-based" file formats, which are used by everyone. JPEG files are a file format in this category, as are ".au" and ".wav" for different types of audio files. Note that the extension only identifies the type of file—it does not determine it. If you were to take a Word file named LessonPlan1.doc and simply change its name to LessonPlan1.jpg, it's still a Word document file, not a JPEG. Once you change the name, however, Word may no longer be able to open it because it will think it's a JPEG file because of the extension, even though the format won't match the JPEG standard.

In order to change the format of a file, you must create or open it in an application that understands that file format, then do a "SAVE AS" to the format you want. The program will then automatically change the file format and assign the right extension.

Here's why file formats and extensions are important:

• As we've said, programs can only open file formats they understand, and the extension, in most cases, needs to match the format. (For example, Word is a word processor; it doesn't understand sound or graphics files, so it can't open them. It can, however, understand a variety of text formats.)

• Formats are for particular uses, such as sound, video, text or graphics. Even within those types, some formats are better for particular uses. JPEGs and GIFs are especially suitable for graphics on Web pages, whereas Postscript files (.ps) are much better for printed graphics.

• As you browse the Web, you may encounter certain files that you want to download to your computer and open. Your browser needs to know what program to use to open them. Although most popular extensions are assigned to certain programs when you first install your browser, you may encounter unknown file types over time or decide that you want to use a different program to open certain file types. For example, PDF files are a special type of file that is popular on the Web. It was created by Adobe to deal with the problem of different file types. It lets people transfer highly formatted documents (such as those that include colors, fonts and graphics) between computers that may not have the programs necessary to display them, and it prevents people from changing the files once they are sent. In order to open a PDF file, you'll need Adobe's Acrobat Reader, which is free at Adobe's site in it's basic version. We recommend that you install Acrobat Reader on your lab's computers because the PDF format is so popular.

It's a good idea to get an overview of some of the most common file types used on the Web. Don't worry, you don't have to memorize a lot of technical jargon. In most cases, you'll only be working with a few popular file formats and your applications will handle things automatically; however, you do need to understand the concept of file formats and the SAVE AS function when moving files from one application to another. Note, by the way, that the SAVE AS command is not just for changing file formats. You might do a SAVE AS sometimes simply to change a file name without changing the format.

The Name's the Thing

We've spent a lot of time talking about the extensions that come after the "dot," but more important for daily practice is what comes before it. You must teach and model the importance of giving files logical names so that kids can identify their files when they need to. Every experienced computer user has suffered from many common mistakes, so use the following guidelines so that you and your students will have good file-handling habits.

• Give your files clear names so that a month from now, you aren't searching through short, coded tags you no longer understand. This rule is especially important when working with devices like digital cameras and scanners. In many cases, software will simply assign new files the same default name each time you start up the program. For example, every time you turn on the camera and start taking pictures, it will likely just start naming files photo1.jpg, photo2.jpg, etc. If you have a disk in the camera that already has a file named photo1.jpg on it, poof! That file will disappear, overwritten by the new picture. The same i's true if you copied that old photo to the computer hard drive without renaming it: If the new photo is transferred without renaming it, the older one will be overwritten.

• Always have kids label their disks with names they'll remember, including dates and the projects they're working on. You'll have lots of floppies laying around, and you don't want to accidentally set an unlabeled disk in a big pile of others. You also don't want kids to forget which disk is theirs if they're working on a project over time.

• Although it has nothing to do with naming, model the importance of saving your files regularly. There's nothing more maddening than working for hours on a project, then losing everything because the computer freezes up or there's a power surge. Despite the fact that we all know the importance of saving our work, it's another trauma that every veteran computer user has suffered more than once. Similarly, make sure that you back up your computers regularly.