Adding a landmark to return to a place once you've found it in Second Life is easy- just go to the "World" menu and click "Create Landmark Here". Once you do this, a landmark is created in your inventory folder that you can then right click on and select "Teleport" to return to that spot anytime its available.
You can drag and drop landmarks onto another avatar or to their drop box on their profile to pass them around, and you can also attach them to a note card in your inventory- this is a great way to build "tours" or guided experiences in Second Life. The next time you're wandering around exploring spaces for your teaching practice, make a note card, and annotate each landmark in the note card to pass off to others. We love trading these to share our Second Life discoveries!