The fragments section is quite simple, and does not explain much about Fragments, except their use in improving modularity within your app. In their example, they show you how to use 2 activities for a phone layout, and 1 activity with 2 fragments for a Tablet layout. Pretty simple.
The course highlights the importance of libraries, and first points to the usefulness of the Android Support Library. It is pretty important, since I often forget that it is even a library to begin with. Here are two nice resources which highlight some of the most important libraries for Android:
Then the course goes through an example app using the Google Mobile Vision library to overlay emoji’s over faces in a photo. Pretty nice.
And finally, the course concludes by suggesting that you make your own library.
FCM – Firebase Cloud Messaging
This section mostly just goes over the same tutorial as if you Googled “how to add FCM to Android” and went through that result. Useful if you haven’t used Firebase before. It’s a pretty powerful and efficient platform. One thing that I like is that they go over the SubscribeToTopic functionality, which wasn’t obvious from my previous work on Firebase.