Every file on your machine ends with a short tag after the dot: {{code:.docx}}, {{code:.pdf}}, {{code:.jpg}} and so on. That tag is the file type, and it tells the computer which app should open the file. Today you will learn to read those tags at a glance so you stop guessing, stop double-clicking the wrong thing, and pick the right format when you send finished work for your Something Real project.
Look at this filename. Without opening it, what kind of file is it, and would you expect to edit it easily or mainly read and send it?
| Filename | Your quick guess |
|---|---|
| {{code:work_experience_report_final.pdf}} | Type? Easy to edit, or mainly read and send? |
Keep your answer ready. We will come back to PDFs in a few minutes.
A file extension is the short code after the final dot in a filename. It is not decoration. It is the label that links the file to the right application.
Today we lock four anchors. The full set of common extensions stays on screen as a quick-reference card you can look up during the sort and Portfolio Build.
| Concept | Why it matters | Example |
|---|---|---|
| File extension — the letters after the final dot (for example {{code:.docx}}) | Tells the computer which app should open the file | {{code:placement_hours.xlsx}} opens in Excel Online or Google Sheets, not a photo app |
| docx vs pdf — {{code:.docx}} is editable; {{code:.pdf}} keeps a fixed layout | Draft in docx; send finished work as pdf so layout does not shift on someone else's machine | Your Something Real proposal stays {{code:.docx}} while you edit; the version you email a supervisor is {{code:.pdf}} |
| Opening the wrong format — forcing a file into an app that does not understand it | You get garbage text, a blank window, or a false "corrupt file" message | A {{code:.docx}} opened in a plain text editor looks like code mess; the file is fine, the app is wrong |
| Zip archives ({{code:.zip}}) — one compressed package that can hold many files | Email and uploads often cap size; zip several files into one attachment | Three product photos plus a price list become {{code:promo_assets.zip}} |
Back to {{code:work_experience_report_final.pdf}}. It is a finished, fixed-layout document. You mainly read and send it; full edit is not the point. That is the PDF rule in one line.
Use this card during the sort and Portfolio Build. Pair twins share a job family.
| Extension | Job | Open with |
|---|---|---|
| {{code:.docx}} | Draft and edit text | Word Online or Google Docs |
| {{code:.pdf}} | Finished work to read and send | Browser or PDF reader |
| {{code:.xlsx}} | Budget, tracker, tally | Excel Online or Google Sheets |
| {{code:.pptx}} | Slide deck / pitch | PowerPoint Online, Google Slides, or Canva |
| {{code:.jpg}} / {{code:.png}} | Photo (jpg) or sharp logo, often with clear background (png) | Photos, Preview, browser, or image editor |
| {{code:.mp3}} / {{code:.mp4}} | Audio only (mp3) or video (mp4) | Media player in the browser or OS |
| {{code:.zip}} | Compressed package of several files | Extract first, then open the files inside |
Your Portfolio Build uses this three-column shape. One sample row only — you will fill ten new names yourself.
| Filename | Type | Open with |
|---|---|---|
| {{code:sample_name.docx}} | Word-processed document | Word Online or Google Docs |
As a class, sort each filename into the application that should open it. First talk the placements through. Then drag the cards and use Check to confirm. Use the quick-reference card on screen if you need a nudge — read the extension, do not guess from the name alone.
| Issue | Solution |
|---|---|
| I cannot see any extension on my filenames | Your device may be hiding extensions. On Windows, open File Explorer, go to View and tick "File name extensions". On a Mac, in Finder use {{menu:Finder -> Settings -> Advanced}} and tick "Show all filename extensions". On a Chromebook, extensions usually show in the Files app by default. |
| I double-clicked a file and got nonsense text or a blank window | The file is probably fine; the wrong app opened it. Check the extension, close the window, and open the file from inside the correct application (or right-click and choose Open with). |
| I sent a {{code:.docx}} and the other person says the layout looks broken | Export or save a {{code:.pdf}} copy for finished work. PDF keeps fonts, spacing and images stable across different machines. |
| I cannot open a {{code:.zip}} like a normal folder of photos | Extract or decompress it first. On Windows, right-click the zip and choose Extract All. On a Mac, double-click the zip. On a Chromebook, double-click the zip in Files. Then open the files that appear. |
We are all building this now. On the teacher's count, open {{code:Project_Portfolio}} then {{code:01_brief}} on screen before anyone creates a document. If {{code:01_brief}} is missing, create that folder inside {{code:Project_Portfolio}} first, then continue.
The quick-reference card from Key concepts stays on screen as a legitimate support for everyone. Use it for layout and lookup; do not copy old answer rows that are not on this list.
You're previewing this lesson. Get full access to this lesson and hundreds more — each one ready to teach, with interactive activities, printable resources and pupil progress tracking built in.