C. What Are Data and Visualization?

← B. Where Does Data Come From? ⏱️ 5 min D. Bar Graphs →

🎯 Learning Goals

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

○ You understand what data and visualization are
○ You can explain why we need graphs
○ You can draw a simple line with the turtle

Core Concepts

What Are Data and Visualization?

data and visualizationis turning numbers into pictures!

📊 Analogy: Report Card vs. Graph

As numbers: Korean 85, Math 92, English 78, Science 88
As a graph: You can see at a glance that Math is the highest!

Numbers alone are hard to compare, but with a graph you can understand right away !

Why Do We Need Visualization?

Situation	Numbers only	With a graph
Comparing scores	You have to figure out which subject is higher	Compare instantly by bar height
Trend over time	You have to read the numbers one by one	Grasp it instantly from the slope of the line
Checking proportions	You need to calculate percentages	Check it instantly with a pie graph

See Example Graphs

Let's see what a real graph looks like! Press the Run button.

📊 Bar Graph (Bar Chart)

Used to compare sizes across categories!

Advantages of bar graphs

At a glance, you can see that Math is the highest, and English is the lowest!

📈 Line Graph (Line Chart)

Used to see changes over time!

Advantages of line graphs

You can see at a glance that the temperature keeps rising from January to June!

🥧 Pie Graph (Pie Chart)

Used to see the proportion of the whole!

Advantages of pie graphs

Apples make up 35% of the total—you can tell right away that they're the most popular!

Types of Graphs

Graph type	Use
📊 Bar graph	Comparing sizes
📈 Line graph	Trend over time
🥧 Pie graph	Showing proportions
🗺️ Other	Maps, heatmaps, etc.

Try Visual Coding

Let's draw a simple line with the turtle. This is the foundation of a graph!

🎯 Mission

○ Add the turtle start block

○ Add a block that moves forward 100

# Add blocks and the Python code will show up here...

Add blocks and the flowchart will show up here...

Example Code

import turtle

t = turtle.Turtle()
t.shape("turtle")

# Draw a simple horizontal line - the foundation of a graph!
t.forward(200)

What Happens

The turtle draws a line to the right. This line becomes the foundation of a bar graph!

⚠️ Try Breaking It (Let's Break It!)

Look at the data below. Which graph would be best?

Mon	Sales
Jan	100
Feb	120
Mar	90
Apr	150

Choices

A) Pie graph
B) Line graph
C) Bar graph

Show Answer

B) Line graphis the best fit!

Data characteristics	Best graph
Used to see changes over time	Line graph 📈
Comparison across categories	Bar graph 📊
Proportion of the whole	Pie graph 🥧

Monthly sales are data that show Used to see changes over time, so a line graph that shows the trend well is the best fit!

🎯 Quiz

Quiz: Choosing a Graph

What's the best graph to show "the proportion liking each fruit"?

Show Answer

Answer: C) Pie graph (showing proportions)

When showing "proportions," a pie graph is the best fit! It treats the whole as 100%, so you can see at a glance the share each part takes up.

Line graph: change over time
Bar graph: by category Size Comparison
Pie graph: relative to the whole Proportion

Fill-in-the-Blank Practice

Data and visualization and graph types:

Data and visualization turn numbers into pictures
Change over time: a graph
Proportion of the whole: a graph
Comparison across categories: a graph

Try Coding It Yourself

Draw a Plus Shape

Draw a plus (+) shape with the turtle. It's like the X-axis and Y-axis of a graph!

Example Answer

import turtle

t = turtle.Turtle()
t.shape('turtle')

# Horizontal line
t.forward(100)
t.backward(200)
t.forward(100)

# Vertical line
t.left(90)
t.forward(100)
t.backward(200)

Result: A plus shape is drawn! These are the axes of a graph.

🧩 Key Takeaways

What you learned in this lesson:

Concept	Description
data and visualization	Turning numbers into pictures
Advantages	You can understand information at a glance
Graph type	Bar, line, pie graphs, etc.
Using the turtle	Make a graph by drawing lines

Review Checklist

[ ] Can you explain what data and visualization are?
[ ] Do you know why graphs are better than numbers?
[ ] Can you draw a line with the turtle?

← B. Where Does Data Come From? ⏱️ 5 min D. Bar Graphs →