Why Children’s Grammar Mistakes Are Smarter Than You Think

For decades, scientists have been fascinated by these kinds of errors. Why do they happen? What do they reveal about how children learn grammar? And why are some verbs—especially irregular ones, like “go” (went) or “buy” (bought)—so tricky to master? To answer that, researchers have proposed two major ideas about how kids learn language.

Two Roads to Grammar: Rules or Patterns?
 

One view says children have two systems in their brains. One is like a grammar machine—it builds past tense forms using rules (like “add -ed”). The other is more like a memory bank—it stores exceptions like “went” and “broke.” According to this dual-system theory, kids first learn some verbs by memory. Then they figure out the rule and start using it—sometimes too enthusiastically. That’s when “go-ed” and “runned” start showing up. Eventually, their memory catches up and corrects these overuse errors.

The other idea is that kids learn everything through experience—by hearing language, picking up patterns, and making smart guesses. This usage-based approach sees errors not as mistakes, but as stepping stones. Children build their understanding of grammar from the ground up, drawing connections between words that sound or work alike over time, like “jumped” and “helped.”

What Can Children’s Language Errors Teach Us?

At first glance, it might seem like children’s grammar mistakes are just slips of the tongue—adorable, but not very meaningful. In reality, these little “errors” are like windows into the mind. They reveal how children are actively testing out the rules of language, making guesses, and adjusting based on what they hear.

Here are a few kinds of errors and what they tell us:
 

1. Omissions: “He go school yesterday”

   When children leave out the past tense marker (“-ed” in English, or a vowel change in Dutch), it might seem like they’ve just forgotten. But often, this shows they haven’t yet fully connected the verb to its past form. It could also mean that they’ve heard a lot of sentences without tense markers, which are  word endings that show something happened in the past, (we do this more often in casual speech than we think!) and they’re reflecting that back.

   
   What it tells us: Children are really good listeners. When they leave out parts of words, it’s not because they don’t know better—it shows they’re still tuning into the language around them. Their learning happens step by step, sometimes making stops and starts along the way, rather than in one smooth, perfect path.

    

2. Overregularization: “She go-ed to the shop”
   
   This one is famous. Kids learn the pattern “add -ed” and apply it to everything, even verbs that don’t follow that rule. To an adult, this sounds wrong—but to a linguist, it’s the sound of a child working out the grammar system.
   
   What it tells us: Children are discovering rules! They’re not just repeating memorized phrases. They’re applying logic and testing out patterns. This shows that rule-learning happens early—and sometimes, a little too enthusiastically.
    

3. Overirregularization: “My sister truck me”
   This type is rare but especially interesting. It’s when a child uses an irregular pattern on a regular verb. Why? Because they’ve heard irregular pairs like stick / stuck often enough, they start to believe that other past tense verbs might work like that too.
   
   What it tells us: Children aren’t just learning individual words—they’re noticing deep patterns in the language around them. This kind of error shows that kids make analogies: “If stick becomes stuck, maybe trick becomes truck?” It’s a glimpse into their mental detective work.

Why These Mistakes Matter

These “errors” aren’t failures—they’re experiments. Each one reflects a child’s current understanding of language, shaped by memory, frequency, sound patterns, and experience. By studying these mistakes, scientists learn how language is built in the brain: not by memorizing rules in a book, but through active problem-solving, trial and error, and constant adjustment.

In other words, children aren’t getting language wrong. They’re learning it, step by step—out loud.

Growing Into Grammar

What’s clear is that these patterns change as kids get older. Younger children tend to make more regular-rule mistakes, while older kids start to get the trickier forms right—especially if they hear them often. This change over time helps us see not just what children know, but how they come to know it.

Language learning isn’t instant—it’s a slow, smart process. Whether children are juggling two systems—rules and memory—or just learning through rich experience and pattern-spotting, their “mistakes” with words like buy-ed or go-ed aren’t just errors. They’re stepping stones. Clues that reveal how children build grammar from the ground up, showing us just how creative and powerful those little minds really are.

Bibliography

1. Matthews, D. E., & Theakston, A. L. (2006). Errors of Omission in English-Speaking Children’s Production of Plurals and the Past Tense: The Effects of Frequency, Phonology, and Competition. Cognitive Science, 30(6), 1027–1052. https://doi.org/10.1207/s15516709cog0000_66

2. Marcus, G. F., Pinker, S., Ullman, M., Hollander, M., Rosen, T. J., Xu, F., & Clahsen, H. (1992). Overregularization in Language Acquisition. Monographs of the Society for Research in Child Development, 57(4), i–178. https://doi.org/10.2307/1166115

3. Maslen, R. J. C., Theakston, A. L., Lieven, E. V. M., & Tomasello, M. (2004). A Dense Corpus Study of Past Tense and Plural Overregularization in English. Journal of Speech, Language, and Hearing Research, 47(6), 1319–1333. https://doi.org/10.1044/1092-4388(2004/099)