Children use ordinal numbers (first, second, third, ..., tenth) to describe position in a sequence or line. Ordinal numbers extend counting to indicate order or rank.
Line up children or objects and identify their position ("You are first, you are second"). Race games where you identify places. Read books with position language.
Mixing up ordinal and cardinal numbers (saying 'first' means 1 item rather than position). Struggling with teen ordinals (11th, 12th).
You already know how to count: one, two, three, four... up to ten. Counting tells you how many things there are. But sometimes you don't want to know how many — you want to know which one. If five friends are standing in a line, you might want to know "who is at the front?" That is where ordinal numbers come in. Ordinal numbers tell you about position or order: first, second, third, fourth, fifth, sixth, seventh, eighth, ninth, tenth.
Every counting number has a matching ordinal. One goes with first, two goes with second, three goes with third. After third, the pattern gets more regular: four → fourth, five → fifth, six → sixth, and so on to ten → tenth. When you are in a race and you cross the finish line before everyone else, you come in first. The next person comes in second. The last person in a group of ten comes in tenth. The ordinal tells you where you are in the sequence, measured from the front.
An easy way to remember the difference: if you ask "how many apples are in the bowl?" the answer is a counting number — maybe five apples. If you ask "which apple did I pick up first?" the answer is an ordinal — the first one, or the third one from the left. Counting numbers (1, 2, 3...) tell you quantity. Ordinal numbers (first, second, third...) tell you position or rank.
You use ordinal numbers every day without noticing. When someone reads a story and says "turn to the third page," that is an ordinal. When a game says "Player 1 goes first," that is an ordinal. When you line up for lunch, knowing you are second in line means one person is ahead of you. As you keep learning, ordinal numbers will help you understand sequences, rankings, and the order that things happen — all ideas that grow from the simple idea of knowing your place in a line.