The Language Explosion
Around 18–24 months, most toddlers experience what researchers call the "vocabulary explosion" — a period of dramatically accelerating word acquisition that can see children adding several new words per day. By age 2, most children have between 50 and 200 words. By age 4, they have several thousand, and can construct grammatically complex sentences, tell simple stories, and engage in genuine conversation. The window between 20 months and 4 years is one of the most intensive periods of language learning in a human lifetime.
What Supports Language Growth
The research on language development consistently points to one primary driver: the quantity and quality of talk the child is exposed to and engaged in. Not passive exposure to speech — not television, not background conversation — but speech directed to the child, conversational, responsive, and connected to what the child is actually experiencing in the moment.
This means narrating what you're doing together: "I'm putting your shoes on. First this one, then this one. Now you can walk." It means asking open questions that invite more than yes or no: "What do you think will happen if we add more water?" It means reading aloud — not just stories, but also books about real things, pointing and naming, and letting the child set the pace.
Screens and Language
The research is consistent and worth taking seriously: screen time in the first two to three years of life — including so-called "educational" content — does not support language development in the way that live conversation with a person does. Children learn language from people, not from screens. The contingency of real conversation — where what is said depends on what the child just said or did — is what drives language acquisition. Screens cannot provide this.
When to Be Concerned
Language development varies significantly between children, and variation within a broad range is normal. However, some milestones are worth tracking: by 12 months, some words; by 18 months, at least 10–20 words; by 24 months, two-word combinations ("more milk," "daddy go"). If your child's language is significantly behind these benchmarks, or if they are losing words they had previously, it is worth discussing with your doctor. Early intervention, when needed, makes a significant difference. Waiting and hoping rarely does.