Title Card: Creator: Parisa Setayesh | Level: Beginner | Category: Data: Data, Space and Place

Why this matters
A lot of mapping becomes less mysterious once learners understand the basic data models. QGIS’s introductory documentation explains that vector data represents real-world features as points, lines, and polygons, while raster data represents space as a grid of values and is especially useful for continuous phenomena. It also stresses that vector features carry attributes — the descriptive information that makes maps analytically meaningful rather than merely locational.

Key ideas

• Vector data represents discrete features.
• Raster data represents continuous surfaces.
• Attributes describe features and make thematic mapping possible.
• Choosing the wrong data model can flatten or distort the phenomenon you want to show.

Lesson
This lesson should introduce learners to one of the most basic but important distinctions in spatial work: not every real-world phenomenon behaves like the same kind of data. A subway stop might be mapped as a point. A street as a line. A neighborhood or census tract as a polygon. Surface temperature, elevation, or satellite imagery is often better represented as raster. That is not just a technical classification; it affects what kinds of patterns a user can perceive and what kinds of analyses become possible.

Equally important is the relationship between geometry and attributes. A polygon is not useful just because it has a shape; it becomes useful when it can be linked to data such as population, rent burden, tree canopy, or voting results. This lesson should help learners understand that mapmaking is always about that pairing: where something is, and what we know about it.

Example Project or GCDI resource
Getting Started with Social Explorer: A GC Resource for Spatializing Demographic Data, Part 1 is a strong GCDI example for this lesson because it is explicitly about turning demographic information into mapped geography. Even from the title alone, it models the move from tabular data to spatial interpretation.

Open reading / resource
A strong companion bundle is A Gentle Introduction to GIS from QGIS, especially the sections on Vector Data, Vector Attribute Data, and Raster Data. These pages are unusually beginner-friendly and match the level you want for Mapping Commons.

Reflection / mini activity
Take one local issue — for example street safety or urban heat. List:

• one thing you would map as points
• one thing you would map as lines
• one thing you would map as polygons
• one thing you would map as raster

Then explain why each format fits that phenomenon.