Bottom sheets are like toasts in the sense that they allow the user to keep doing what they are doing, but different, they are the notifications that appear at the bottom of the screen that a user can dismiss, they (like toasts) also don’t block the current screen
The global function (showBottomSheet or modalBottomSheet) expects a BuildContext and a WidgetBuilder. The modal displays over UI elements, so keep that in mind
the WidgetBuilder (That closure you should be familiar with from alerts for example, or a full fledged function definition, your choice) and the build context (you should have been passing around already by now) are straight forward, what is not is that a bottom sheet must be called with a context that contains a Scaffold. in other words, you’ll have to be “under” a scaffold widget… so to rephrase, it shows a Material Design bottom sheet in the nearest [Scaffold] ancestor
Now, to understand the problem, the context we are passing around as we put it in the last paragraph, belongs to the top-level widget, that widget has a scaffold obviously, but the scaffold is under it, when our bottom sheet wants to attach to a widget, using the of-context pattern to find the scaffold will fail as we are looking up the tree not down where the scaffold is !