If you were marking location, consider what you'd really be saying in English. > I brush on my teeth, wash on my face, and have breakfast every day. When you're using で you'd indicating where the action is occurring. Consider how odd this sounds in English. It's the same in Japanese: unless there's something on your teeth that you were brushing or something on your face that you were washing. If you're using で to mark the location of an action, you're marking the location within which the action was occurring. > 図書館で本をよみました。 > I read my book at the library. You could say > 台所で歯を磨いて。。。 > I brushed my teeth in the kitchen and .... If you're thinking of your teeth or your face as a *tool*, then the rendering in English would be to the following affect: > I brushed with my teeth, and I washed with my face.... Hopefully, you're not using your teeth as a tool for brushing something (you'll wear your teeth away and there are probably better *tools* available). When you're brushing your teeth, you're using a toothbrush, not your teeth. > 歯ブラシで歯をみがきました。 > I brushed my teeth with a toothbrush. And unless you're into strange sexual practices, you're probably not washing anything with your face. > ハンドタオルで顔を洗った > I washed my face with a washcloth.