Computer Skills

Beginner

60 mins

Teacher/Student led

+90 XP

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

The Numbers — Spreadsheets for Real Decisions

Turn your project proposal into a working spreadsheet with real formulas. Learn to build budgets, inventories, and data summaries that update automatically when numbers change.

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1 Introduction
2 Key Concepts
3 Step-by-step Task — Galway Trip Budget
4 Common Issues
5 Pick Your Shape
6 Portfolio Build — Your Numbers Sheet
7 Reflection
8 Lesson Summary
Quiz

1 - Introduction

Illustration for Introduction

Welcome

Your proposal from the previous lesson looks sharp, but it is still just words. Today you turn it into something a parent, teacher, or principal cannot argue with: numbers that add themselves up. A spreadsheet with real formulas is the quiet difference between "I think we need about €500" and "Here is exactly where every euro goes, and if one item changes, the total changes with it."

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

Navigate a spreadsheet using cells, rows, and columns
Enter data and format numbers as currency
Write formulas using SUM, AVERAGE, COUNT, MIN, and MAX
Use autofill to copy a formula down a column
Build your own Numbers Sheet for your Something Real project

Warm-up

Think of one question about your Something Real that starts with "how much" or "how many". (How much will the trip cost per person? How many volunteers do we need? How many weeks until launch?) Now write that question down — in your notebook, on a sticky note, or as the very first line at the top of the new spreadsheet you're about to create in a few minutes. Don't skip this. At the end of today you'll check it against the number your spreadsheet gives you.

Teacher Notes

Students should bring their Something Real project from the prior module — their proposal gives them the content to build numbers around. If you see students staring into space during the warm-up, point at paper and say 'write it, don't just think it'.

👇 Mark your steps as done as you complete them.

+5 XP

2 - Key Concepts

A spreadsheet is a giant grid of boxes (cells) that can do maths for you. The rest is just details.

Concept	Why it matters	Example
Cell, row, column — every box has an address made of a column letter and row number	Formulas refer to cells by address, so {{cell:B2}} always means the same box no matter what's inside it	{{cell:B2}} is column B, row 2 — the cost of your first trip item
Formula — a calculation you type into a cell, always starting with `=`	The sheet does the maths for you, and if you change an input the answer updates instantly	Type {{formula:=B2*C2}} and the cell shows the result (e.g. 600), not the text of the formula
Relative cell reference + autofill — drag the small square at the bottom-right of a cell to copy a formula down, and the references shift with each row	Write one formula, get ten — you don't retype `=B2C2`, `=B3C3`, `=B4*C4`…	Autofill {{formula:=B2*C2}} from {{cell:D2}} down to {{cell:D6}} and each row calculates its own total automatically
Functions: SUM / AVERAGE / COUNT / MIN / MAX — pre-built formulas that work on a range of cells	One function replaces a long manual sum and keeps working when you add new rows	{{formula:=SUM(D2:D6)}} adds up five total costs to give you the whole trip budget in one cell

What a Numbers Sheet looks like

Below is the shape you'll build in the worked example — a Galway trip budget. Your own sheet (later) can be a budget, a timeline, survey results, or an inventory, but the structure stays the same: headings on top, data rows in the middle, summary formulas at the bottom.

A	B	C	D
Item	Cost per person (€)	Quantity	Total (€)
Coach hire	25.00	24	600.00
Museum tickets	8.00	24	192.00
…	…	…	…
Total cost			1,542.00
Most expensive			600.00

👇 Mark your steps as done as you complete them.

+10 XP

3 - Step-by-step Task — Galway Trip Budget

Build a working budget for a fictional Transition Year trip to Galway. You'll enter data, write formulas for the total per item, and use five summary functions. This is the shape you'll reuse for your own project straight afterwards.

Teacher Notes

Pacing: 20 minutes is tight once you include the 'how do I select a range?' moments and the magic-update test at the end. If a slower group is still on the SUM row at 15 minutes, stop them there, hand out the remaining functions as a warm-up next lesson, and get everyone onto the Portfolio Build on time.

+15 XP

4 - Common Issues

Common Issues

Issue	Solution
My cell shows `=B2*C2` as text instead of a number	The cell is formatted as Text. Select the cell, change the format to Number, then re-type the formula starting with `=`.
I see `#VALUE!` or `#REF!` in a cell	`#VALUE!` usually means a formula is pointing at text (check for a stray letter in a number column). `#REF!` means a referenced cell was deleted — undo with {{kbd:Ctrl+Z}} / {{kbd:Cmd+Z}} and try again.
Autofill gave me the same number in every row instead of different totals	You probably dragged down from a cell with a fixed value rather than a formula. Delete the filled cells, click back into {{cell:D2}}, check it starts with `=`, then drag again.
My currency shows $ instead of €	Your app is defaulting to US currency. Pick the range, open the currency format menu, and select Euro (€) or "More formats" → Currency → Euro.

+10 XP

5 - Pick Your Shape

Before you build your own sheet, pick the shape that fits your Something Real. Each shape uses the same three-part structure you just practised (headings → data rows → summary formulas), but the columns and the formulas that make sense will differ.

Shape	Suggested columns	Formulas that fit
Budget (trip, event, fundraiser)	Item · Cost per person · Quantity · Total	SUM total spend · MAX biggest expense · AVERAGE item cost
Timeline (event prep, launch)	Task · Week · Hours needed · Person responsible	SUM hours · COUNT tasks · MAX heaviest week
Survey results (demand evidence for a proposal)	Question · Yes · No · Maybe	SUM responses per question · MAX most popular answer · AVERAGE support
Inventory (what to buy or borrow)	Item · Unit price · Quantity · Total price	SUM total cost · COUNT items · MIN cheapest item

If none of these quite fit, invent your own — as long as you have at least 5 rows of real data and at least three different summary formulas, you're good.

Teacher Notes

Steer students toward Budget or Inventory if they're still shaky on formulas (both share the same numeric shape as the worked example). Timeline and Survey results work best for confident students.

+10 XP

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

The Numbers — Spreadsheets for Real Decisions

Teacher Class Feed

1 - Introduction

Welcome

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

Warm-up

2 - Key Concepts

What a Numbers Sheet looks like

3 - Step-by-step Task — Galway Trip Budget

4 - Common Issues

Common Issues

5 - Pick Your Shape

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