What is Class in Math?
A set or group containing members regarded as having certain attributes or traits in common
In math, a class is a group of numbers or objects that share something in common. You can think of a class as a “category” or “collection” where everything inside it fits a certain rule or has a shared trait.
Examples of classes students often encounter include:
Even numbers: Numbers that can be divided by 2 with no remainder (e.g., 2, 4, 6, …)
Triangles: A class of shapes with exactly three straight sides (e.g., all shapes with 3 sides)
Prime numbers: Numbers greater than 1 with only two factors: 1 and themselves (e.g., 2, 3, 5, 7, …)
Fractions less than one: Fractions where the top number is smaller than the bottom, showing part of a whole (e.g., \(\displaystyle\frac{1}{2}\), \(\displaystyle\frac{3}{4}\))
When students truly understand what classes are, they can more easily:
- Sort and organize math objects: Like grouping all the triangles in a set of shapes, or separating odd and even numbers
- Understand properties of numbers: For example, realizing that all prime numbers only have two factors, or that all multiples of 5 end in 0 or 5
- Compare and analyze patterns or rules: Such as noticing that every even number is two more than the last, or that all right triangles share a 90° angle
In more advanced math, "class" can also be used in set theory and logic to describe collections of things that may or may not be sets themselves.
Classes in Data and Statistics
The word "class" can also refer to a concept in data and statistics, especially when students begin working with graphs and charts in upper grades.
In this context, a class refers to an interval or range of values used to group data. These are known as class intervals and are commonly used in histograms which is a type of bar graph that shows how often values fall within certain ranges.
We will explore classes in data and statistics more in our upcoming definitions.
When Do Students Learn About Classes?
Students begin learning about classes informally when they start sorting and classifying objects by attributes, then apply this thinking to numbers and shapes.
Kindergarten – Sorting and Grouping
Students sort objects by size, color, shape, and other features, building early classification skills.
Grades 1–2 – Grouping Numbers and Shapes
Students learn to group numbers (like even vs. odd) and shapes (like triangles vs. squares), laying the groundwork for understanding math classes.
Grades 3–5 – Classifying by Properties
Students classify numbers (prime, composite), shapes (polygons, quadrilaterals), and data. They begin using rules to define classes clearly.
