I'm trying to add an Assets folder to my Android Project in Android Studio 2.1.2. I right click on the project and choose New -> Folder -> Assets Folder. In the project pane on the left, it doesn't show up when Android is selected. If I switch to Project Files, it does appear, however it looks like a normal directory, rather than looking like a resource directory. I then tried adding files to it (jpgs), both through Android Studio and through the file explorer (all file names are lowercase with no special characters). If you unzip the apk that gets created though, it doesn't contain an Assets directory or the added files. Also sometimes the assets directory will disappear from the project files pane, although it's still in explorer.
What step am I missing to get to the Assets directory properly added to my project?
Note: this is for a LibGdx project that expects image files to be there.