Vocabulary explosion

What happened? Over the last several weeks I've suddenly become quite a chatty cathy. My parents believe that I developed a lot of my vocabulary and speech mannerisms at school. I like to tell stories in a sing-song voice, "xxx, an den [and then], *tsk*, xxx, an den..." If my parents are not paying attention, I scold "guys, don't talk!" If they ask me a question, I might reply "I don't know" and shrug my shoulders. If they ask me to do something, I may say "I did already" and raise both hands out to the side. My parents can't get over the conversations we have now. I'm not a baby any more!