Guidelines for the development of normal speech and language skills:
Have command of 200 to 300 words and can learn one or two new words every day.
Two to three years:
Vocabulary has grown to about 1,000 words. Children can form simple sentences of three and four words, and can construct a sentence containing a subject and a verb.
Three to four years:
Vocabulary should be about 1500 words. Sentences become longer and more complex. They can tell little stories and recount recent events. They will typically struggle with negative words – no, not, can’t, don’t – and will attempt to add endings to words such as –s, -es, and –ed.
By age five:
Vocabulary exceeds 2000 words. Children have mastered most sounds. They can use sentences with correct grammar 90% of the time. They should be able to express their feelings and follow 3 step commands.