Four to five years:
Your child should be able to communicate easily and boast a vocabulary of about 2,000 words. She should be able to tell you a simple story of something that has happened during her day. She can use a new sentence to describe a picture with most of the grammar elements in place. She will pronounce most sounds correctly but may still have trouble with "th", "r" and "l". She will use lots of descriptive words, including words that refer to time like "this morning" or "yesterday".
Six to seven years:
Your six to seven year old child can describe how two items are the same or different. She will be able to retell a story without the help of pictures and to recount past conversations and events. She will use some irregular plural nouns such as “men” and “teeth”.
Eight years:
By this age she will have conquered all speech sounds as well as getting a handle on the volume and rate of speech. She will use complex and compound sentences correctly and will be capable of carrying on a conversation with an adult.