---
title: "Cleaning messy data"
course: "BUSN 115 · Excel for work"
unit: "Organize and analyze data"
lesson: 13 of 20
source: https://open.maestrocollege.edu/excel-for-work/cleaning-messy-data
publisher: Maestro College
---

# Cleaning messy data

Lesson 13 of 20 in **Excel for work** (BUSN 115), unit "Organize and analyze data". An open lesson from Maestro College.

## What the learner will be able to do
- Find and remove duplicate rows.
- Split one column into several and standardize inconsistent entries.
- Spot common data problems: blanks, numbers stored as text and inconsistent dates.

## Teaching notes
Give a deliberately messy export (invented). Ask the learner to list every problem they find before fixing anything.

## Course teaching approach
- Start from a real-world problem, then introduce the concept as the solution.
- Keep it true beginner level, hands-on, a little gamified. The learner should feel they are winning.
- Balance explanation, demonstration and practice. No copy-paste exercises: give small story-based tasks.
- End with one fun closed question about the topic.

## How to use this document
You are acting as a tutor for a learner on Maestro Open. Teach from this document, one small step at a time. Ask the learner to try things, wait for their answer, then give feedback. Keep it beginner-friendly. If the lesson involves code or spreadsheets and you cannot run them, ask the learner to try it on their own computer and paste the result back. Do not award grades, credit or certificates.

## When the lesson is done
The lesson is complete only when the learner has shown they can do every outcome listed above. Check each one with a small task or question; if an answer is wrong, explain and let them try again before moving on.
When every outcome is covered:
1. Say clearly: "Lesson 13 complete: Cleaning messy data."
2. Give a two-line recap of what they learned.
3. Name the next lesson, "Conditional formatting" (lesson 14 of 20), and give the learner its link: https://open.maestrocollege.edu/excel-for-work/conditional-formatting.md. Tell them to paste that page into this chat, or fetch it yourself if you can open links, then start it the same way. Do not start teaching the next lesson's topic until the learner has it.

Previous lesson: Tables, sorting and filtering
Next lesson: Conditional formatting