If your teen becomes secretive and doesn't want to chat even about how her way went in school, should you consider it normal? Why or why not?

Yes it is very normal for teens to be secretive. Sudden change of behavior happens whenever they go thru adolescence. Their interest changes, style or attitude. At this stage they want to decide on their own or be independent that might cause for them to be secretive. There could be other reasons too. As a parent of 2 preteens. I always tell them to open their ideas, pains and success with me. And that I'm always here to support them. If in any case that they might have made wrong decisions. I'm always here to guide them to the right solution and still resolve the issue on their own.