1.1: Android Studio and Hello World <- HelloWorldActivity
1.2 Part A: Your first interactive UI <- HelloToastPtA
1.2 Part B: The layout editor <- HelloToastPtA
1.3: Text and scrolling views <- HelloToastPtA
1.4: Learn to help yourself <- (set an icon)

2.1: Activities and intents <- TwoActivities, HelloToastWithIntent
2.2: Activity lifecycle and state <- ActivityLifecycleActivity, (CartActivity, ShopActivity)
2.3: Implicit intents <- ImplicitIntentsActivity, (OneTwoThreeFirst, OneTwoThreeSecond)