Earth Science Lesson: Mastering Maps, Graphs & Earth Features

Lesson Overview

• What Is Earth Science?
• Types of Maps and What They Show
• Understanding Graphs in Earth Science
• Grid References – Finding Places on a Map
• Contour Lines – Seeing Land Height on a Map
• Latitude and Longitude – Describing Earth's Location
• Map Symbols, Direction & Ordnance Survey
• Choosing Good Data Ranges for Choropleth Maps
•  Final Review Table
• Key Takeaway:

Have you ever wondered how maps show mountains, where the rain falls the most, or how scientists know the exact location of a city on Earth? That's what Earth Science helps us understand! It's the study of our planet-its land, weather, maps, and the tools we use to explore and explain it.

In this lesson, you'll learn how to read different types of maps and graphs, understand directions, use coordinates, and think like a real geographer. By the end, you'll be ready to answer quiz questions with confidence and curiosity!

What Is Earth Science?

Earth Science is the study of the physical world around us-landforms, oceans, the atmosphere, and even how we use maps and data to understand the planet. It helps us answer questions like:

• What does a mountain look like on a map?
• How can we tell how far north or south a place is?
• How do we track changes in temperature or rainfall?

Types of Maps and What They Show

Choropleth Maps: Seeing Data in Color

A choropleth map uses different shades or colors to show the amount or level of something in an area. For example, darker colors might show higher population density or higher rainfall.

Example: A map of rainfall might use:

• Light blue for low rainfall (0–3 cm),
• Medium blue for moderate rainfall (3–10 cm),
• Dark blue for high rainfall (10–15 cm).

Why it matters: These maps help people easily compare areas based on color.

Think About It:
If two areas are different shades of red, what can you guess about the data in each area?

Understanding Graphs in Earth Science

Geography often uses graphs to show changes or comparisons in data. Choosing the right graph helps others understand your data better.

A. Line Graphs – Tracking Change Over Time

Line graphs are best for continuous data-numbers that change over time like temperature, rainfall, or population.

• The points are connected by lines.
• You can spot trends (like increasing or decreasing temperatures).

Why It Works: A line graph shows patterns clearly and is great for data that changes every day, month, or year.

B. Pie Graphs – Showing Parts of a Whole

Pie graphs or pie charts show percentages of a whole-100%.

• The entire circle is 100%.
• Each slice represents a portion.

When to Use It: When comparing how a total amount is shared between categories, like how a country's land is used (farmland, forest, cities).

C. Bar Graphs – Comparing Categories

Bar graphs use rectangles to compare things.

• A vertical bar graph stands upright.
• Good for comparing things like rainfall in different cities.

A vertical bar graph can be used for 100% data, but a pie chart or divided bar graph is usually better for showing whole parts.

Grid References – Finding Places on a Map

Maps use grid references to help you find exact locations.

A. What Are Grid References?

• Maps have horizontal (left-right) and vertical (up-down) lines.
• Where they cross is a grid square.
• A 6-figure grid reference gives a very precise location within that square.

B. How to Read a 6-Figure Grid Reference

1. Start with the horizontal line (eastings) – go left to right.
2. Imagine the square divided into tenths (10 equal parts).
3. Count how far across (e.g., 3/10 = 3).
4. Then read the vertical line (northings) – go up.
5. Again divide into tenths (e.g., 7/10 = 7).
6. Combine the numbers: e.g., 153723.

 Why tenths? It increases accuracy. Dividing into 10 parts gives a more exact location.

Contour Lines – Seeing Land Height on a Map

A. What Are Contour Lines?

• Contour lines show how high or low the land is.
• They connect points that are the same elevation.
• Found mostly on Ordnance Survey (O.S.) maps.

B. Color of Contour Lines

• Brown is used for contour lines because it's easy to see and doesn't mix with blue water or green forests.

C. What Contour Lines Tell You

• Close together = Steep slope.
• Far apart = Gentle slope or flat land.

Think Like a Scientist:
How could contour lines help hikers?

Latitude and Longitude – Describing Earth's Location

Maps use invisible lines to help describe any point on Earth.

A. Latitude (Lines Go East–West)

• Run parallel to the equator.
• Measure how far north or south a place is.
• Examples: 0° (equator), 45°N (France), 60°S (Antarctica).

B. Longitude (Lines Go North–South)

• Run from pole to pole.
• Measure how far east or west from the Prime Meridian.
• Examples: 0° (Prime Meridian), 120°E (China), 75°W (USA).

Map Symbols, Direction & Ordnance Survey

A. What Is "O.S."?

• O.S. stands for Ordnance Survey, the UK's mapping organization.
• Their maps are very detailed and used for navigation.

B. Compass Directions on Maps

• Most maps include an arrow pointing North.
• This helps you understand which way is up or down on the map.

Pro Tip: Once you know where North is, you can figure out every other direction-East, West, South, Northeast, etc.

Choosing Good Data Ranges for Choropleth Maps

Choropleth maps must have clear and non-overlapping ranges.

Best Practice:

Use ranges like:

• 0–3
• 3–10
• 10–11

These are:

• Easy to understand
• Do not overlap
• Cover all data clearly

Poor Practice:

Avoid ranges like:

• 0–5, 5–10, 10–20
  Why? Some numbers are shared between categories or unevenly distributed.

 Final Review Table

Key Takeaway:

Earth Science gives you the tools to understand and explore your planet. By learning to read maps, graphs, and data, you gain knowledge that helps you navigate, plan, and think critically. Review this guide carefully and reflect on each section, and you'll be ready to ace your Earth Science quiz with confidence!