Ordinal Numbers
What Are Ordinal Numbers?
Ordinal numbers are words like first, second, third, and so on. In many languages, they’re different from cardinal numbers — one, two, three — which we use to talk about quantity. Ordinal numbers are all about order. We use them to describe position in a line, a list, a race, or even a daily routine.
Alongside words like first and second, kids also hear terms like next, previous, last, or even second-to-last — all of which help describe the order of things.
Why Does It Matter for Kids?
Even before they learn the word “ordinal,” kids are constantly dealing with order in everyday life — who’s first in line for ice cream, which car goes next at the light, or what comes after socks when getting dressed. These simple experiences build the foundation for understanding position and sequence — first, second, third, and beyond.
Research shows that kids understand quantity and order as two different ideas, and both are important for building strong number sense. Knowing what comes next (or what came before) helps kids organize their thinking, compare things, spot patterns, and even stick to a routine.
Being able to tell which object is first or second, or what happens next, is more than a life skill. It also lays the groundwork for abstract ideas like number sequences, steps in a process, the flow of events in a story, or the order of instructions in a program.
Understanding the idea of number sequences is a key part of math development, especially in the preschool and early elementary years. Researchers have found that early math assessments — including how well kids understand order — can help predict future success not just in school, but in STEM subjects later on.
Learning to recognize and talk about order builds a bridge to more advanced thinking. It sets the stage for understanding how numbers work, and leads into ideas from logic, algorithms, and algebra.
How Do We Teach?
Ordinal numbers come up naturally when kids wait in line — for ice cream, for a turn on the slide, or to start a game. They also appear at traffic lights, where cars line up one after another. We can talk about the second car in line, or the one that goes right after the red one.
Number sense
Ordinal numbers
Sometimes, the numbers we see don’t match the actual order. A snail wearing number 1 might cross the finish line in second place. And sometimes kids get a set of objects with number stickers in a mixed-up order — and their job is to arrange them from first to last.
Words like first, second, and last often appear in story problems or logic puzzles. For example, the second train car might have twice as many passengers as the first. These words also help kids describe a sequence of actions, such as figuring out which sticker they placed second.
Order sometimes works in reverse. The thing we put on first, like socks, is usually the one we take off last. Talking through examples like these helps kids develop a stronger understanding of order and how steps relate to each other.
Number sense
Numbers and digits
Assemble pictures
Order picture parts
The order of events
Place stickers in order
The order of events
Stacking and unstacking
The order of events
What's the order?
The order of events
What's the order?
Big Ideas
The idea of putting things in order turns out to be important later on too. For example, the number 1/9 can be written as an endless sequence of digits: 0.111111… Numbers like 0.1, 0.11, 0.111, and so on keep getting closer and closer to 1/9, but never quite reach it.
In computer science, order plays a key role as well. Programmers often organize data into sequences. Sometimes they use a structure called a queue — the first item to go in is the first one to come out (first in, first out), just like people waiting in line at the supermarket. Other times, they use a stack — where the last item added is the first to be removed (last in, first out). You can think of it like a tube: you can only pull out the top object, the last one that went in.
