Computer Skills

Beginner

60 mins

Teacher/Student led

+80 XP

What you need:
Chromebook/Laptop/PC or iPad/Tablet

Common File Types & Formats

Learn to recognise common file extensions and choose the right format for different purposes. You'll save a document in two formats and explore when to use editable versus fixed formats.

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1 Introduction
2 Key Concepts
3 Step-by-step Task
4 Common Issues
5 Portfolio Build — File Types Checklist
6 Reflection
7 Lesson Summary
Quiz

1 - Introduction

Welcome

Every file on your computer carries a short tag after the dot, the file extension (like .docx, .pdf, .jpg), that tells the computer which app should open it and what kind of data sits inside. When you're sending work to a Work Experience supervisor, uploading a CV through Intreo, or adding a page to your Digital Portfolio, picking the right format decides whether your file arrives looking exactly as you meant it or whether the person on the other end can't open it at all.

By the end of this lesson, you will be able to:

Recognise common file extensions and what they contain
Choose the right format for a given purpose
Explain when a PDF is the sensible format to send

Warm-up

Imagine an employer emails a job ad that ends with: "Send your CV and cover letter, PDF format only, please." Why would they specifically ask for PDF instead of just "send me your CV"? Think of at least one reason before moving on. You'll check your answer against the Key concepts table in a minute.

Teacher Notes

Invite a couple of warm-up answers aloud before revealing the Key concepts table. Common answers: 'so the layout doesn't break', 'so they can't accidentally edit it', 'so it opens on any device'. All correct.

👇 Mark your steps as done as you complete them.

+5 XP

2 - Key Concepts

Every file type is a different way of packaging information. Some formats are built to be edited, some are built to be shared. Here are the four you'll use most often across Work Experience and your Something Real project:

Concept	Why it matters	Example
File extension — the 3-4 letter tag after the dot in a filename	It tells your computer which app to open the file with.	{{code:payslip.pdf}} opens in a PDF viewer; {{code:payslip.xlsx}} opens in a spreadsheet — same word, two very different files
.docx — Word's editable document format (Google Docs can read and save it too)	Use it while a document might still need changes.	{{code:proposal.docx}} so a placement mentor's suggested fixes can still be typed in
.pdf — a fixed-layout format that locks fonts, images, and spacing in place	Send as PDF when the reader only needs to READ. It looks identical on any device.	{{code:cv.pdf}} sent to an employer so the formatting doesn't break on their phone
.xlsx — Excel's editable spreadsheet format with live formulas	Needed any time numbers should recalculate. A PDF of a spreadsheet is a picture, not a calculator.	{{code:budget.xlsx}} so totals still update when you change a price

Good to know — other formats you'll meet

.jpg / .png — image formats. Use .jpg for photos (e.g. {{code:venue.jpg}}) and .png for logos and screenshots (e.g. {{code:logo.png}}).
.zip — a compressed bundle that packs multiple files into one. Useful when email attachment limits or messy folders would get in the way.

The one-line rule for choosing

If the reader needs to CHANGE the file, send the editable version (.docx, .xlsx, .pptx). If the reader only needs to READ the file, send PDF. If you're not sure, send PDF. It's almost always the safer default for anything leaving your own device.

Teacher Notes

Point out that Google Docs doesn't show a visible file extension in Drive. The 'native' Google Doc is its own thing, but students can download it as .docx or .pdf whenever they need to send it to someone outside Google Workspace.

👇 Mark your steps as done as you complete them.

+10 XP

3 - Step-by-step Task

You'll save one simple document in two formats (the editable version and a fixed PDF) so you can see the difference between edit and share formats hands-on.

Teacher Notes

Students should end this step with TWO files on their device: one editable document (still open in the cloud app) and one PDF downloaded to their Downloads folder. The comparison moment at the end is the whole point, don't let them skip it.

+15 XP

4 - Common Issues

Common issues

If something went sideways during the step-by-step, work through this table before starting Independent Practice.

Issue	Solution
My PDF looks slightly different from the editable version (fonts or spacing shifted)	Some custom fonts don't embed properly when exporting. Use a standard font like Calibri, Arial, or Times New Roman. They're built into every PDF reader.
I can't find the downloaded PDF anywhere	Press {{kbd:Ctrl+J}} (Windows/Chromebook) or {{kbd:Cmd+J}} (Mac) in your browser to open the downloads list, then click the filename to reveal it in your Downloads folder.
I can't see 'Download as PDF' under File > Export in Word Online	Microsoft occasionally moves this option between File > Export and File > Save As. Check both menus, or type "PDF" into the File menu's search box if one appears. Either path produces the same PDF.
Google Docs doesn't save as .docx automatically. It just makes a Google Doc	That's by design. Google Docs uses its own internal format in Drive. Use {{menu:File -> Download -> Microsoft Word (.docx)}} any time you need an actual .docx file to send to someone.
The PDF won't let me edit it at all	That's correct behaviour. PDF is a fixed format. If you need to change the content, open the original .docx or Google Doc, edit it there, and export a new PDF.
I need to insert a table into a document for the next activity and I'm not sure how	In both Word Online and Google Docs, click {{menu:Insert -> Table}} and drag to select the grid size you need (for the next activity, choose 3 columns by 7 rows).

+10 XP

5 - Portfolio Build — File Types Checklist

Independent Practice

Your goal: Map out which file formats you'll actually use across your Something Real project, so that two lessons from now (when you need to send a budget or share a proposal) you already know whether it should go out as .xlsx, .pdf, or something else.

Time: ~20 minutes

Task: Open your {{code:Digital_Portfolio}} folder and create a new document called {{code:06_file_types}}. Inside it, insert a 3-column by 7-row table by clicking {{menu:Insert -> Table}} and dragging across 3 columns and down 7 rows (this works the same way in both Word Online and Google Docs). Use the top row for the headings Format, When I'll use it on my project, and Example filename, then fill the remaining six rows with six different file formats tied to specific moments in your own Something Real project, not a generic textbook list. At least one row must be a PDF moment: something you'll send to a real person (employer, parent, supervisor, school) where PDF is the right choice.

Success criteria:

{{code:06_file_types}} is saved inside your {{code:Digital_Portfolio}} folder with a 3-column table and at least six filled rows, each a different format
Every row names a specific moment in YOUR project, not a generic definition copied from the Key concepts table
One row clearly describes a PDF moment with a specific reader in mind (who's receiving it, and why PDF is right for them)
Example filenames follow the course convention: lowercase with underscores, correct extension (e.g. {{code:budget.xlsx}}, {{code:cv.pdf}})

Teacher Notes

Push students who write generic answers like 'use .docx for documents'. Ask them: which specific document in YOUR project? What moment? The point of the exercise is to connect the format to a real decision they'll make in the next few weeks. If a student can't insert the table from the menu path, walk them to the Insert menu and point at the Table item directly, they'll likely only need to see it once.

+15 XP

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This lesson is copyright of Coding Ireland 2017 - 2025. Unauthorised use, copying or distribution is not allowed.

Common File Types & Formats

Teacher Class Feed

1 - Introduction

Welcome

By the end of this lesson, you will be able to:

Warm-up

2 - Key Concepts

Good to know — other formats you'll meet

The one-line rule for choosing

3 - Step-by-step Task

4 - Common Issues

Common issues

5 - Portfolio Build — File Types Checklist

Independent Practice

Unlock the Full Learning Experience

XP