why do you think so? sometimes I asked my students to do that when I'm teaching the material about sentence pattern to know whether my students are able to identify the word classes or not.
It's not a natural activity that a native English speaker would do. If I wanted to deal with word classes, I'd start by having the students produce and then analyze proper sentences.
However, that's my opinion. If your opinion is that you are getting good results by doing this with your class, it is a matter of your choice.