I am confused about the assets folder. It doesn't come auto-created in Android Studio, and almost all the forums in which this is discussed talk about Eclipse.
How can the Assets directory be configured in Android Studio?
Since Android Studio uses the new Gradle-based build system, you should be putting assets/ inside of the source sets (e.g., src/main/assets/).
In a typical Android Studio project, you will have an app/ module, with a main/ sourceset (app/src/main/ off of the project root), and so your primary assets would go in app/src/main/assets/. However:
If you need assets specific to a build type, such as debug versus release, you can create sourcesets for those roles (e.g,. app/src/release/assets/)
Your product flavors can also have sourcesets with assets (e.g., app/src/googleplay/assets/)
Your instrumentation tests can have an androidTest sourceset with custom assets (e.g., app/src/androidTest/assets/), though be sure to ask the InstrumentationRegistry for getContext(), not getTargetContext(), to access those assets
Also, a quick reminder: assets are read-only at runtime. Use internal storage, external storage, or the Storage Access Framework for read/write content. (note: the first two links are to my blog)