I recently covered search techniques with my students. I showed them Timeline (and privately bemoaned the disappearance of the Wonderwheel - http://searchengineland.com/official-the-google-wonder-wheel-is-gone-84105). Both these tools allowed students to visualize their searches. Today one of my students asked me what happened to the Timeline and I was shocked. She had been using it for history projects. Last year I also showed my students how to search for images with certain usage rights. That option was removed from the left side of the Image Search screen and you now have to click a small wheel icon at the top right to access Advanced Image Search to find it.
Come on, Google. Please stop moving and deleting some of your best features. Some of us are trying to teach students how to use them, and of course, we are using the features ourselves.