A child who says, “My toy car breaked,” or “I runned up the hill,” is demonstrating __________.

Overregularization occurs when a child applies a common grammar rule to an irregular word. The child adds “-ed” to “break” and “run,” producing “breaked” and “runned” instead of “broke” and “ran.” So the answer is overregularization.

AI-written and checked against the verified answer.