Break the form into its own widget, since eventually it'll likely be a pop-up.

lib/main.dart

@@ -2,28 +2,42 @@
 // - https://flutter.dev/docs/cookbook/forms/validation
 
 import 'package:flutter/material.dart';
+//import 'package:provider/provider.dart';
 
 void main() {
   runApp(const MainApp());
 }
 
-class MainApp extends StatefulWidget {
+class MainApp extends StatelessWidget {
   const MainApp({super.key});
 
   @override
-  State<MainApp> createState() => _MainAppState();
+  Widget build(BuildContext context) {
+
+    return MaterialApp(
+        title: 'Recurring Expense Tracker',
+        theme: ThemeData(
+          useMaterial3: true,
+          colorScheme: ColorScheme.fromSeed(seedColor: Colors.green),
+        ),
+        home: Scaffold(
+        body: ExpenseInputForm(),
+        //floatingActionButton: IconButton(onPressed: appState.newExpense(), icon: Icon(Icons.add)),
+      ),
+    );
+  }
 }
 
-class _MainAppState extends State<MainApp> {
+class ExpenseInputForm extends StatefulWidget {
-  final nameFieldController = TextEditingController();
+  const ExpenseInputForm({
+    super.key,
+  });
 
   @override
-  void dispose() {
+  State<ExpenseInputForm> createState() => _ExpenseInputFormState();
-    // Clean up the controller when the widget is disposed.
-    nameFieldController.dispose();
-    super.dispose();
 }
 
+class _ExpenseInputFormState extends State<ExpenseInputForm> {
   @override
   Widget build(BuildContext context) {
     const inputWidth = 400.0;
@@ -37,9 +51,7 @@ class _MainAppState extends State<MainApp> {
       DropdownMenuEntry(value: Recurrence.yearly, label: "Yearly"),
     ];
 
-    return const MaterialApp(
+    return Center(
-      home: Scaffold(
-        body: Center(
       child: Column(mainAxisSize: MainAxisSize.min, spacing: 10, children: [
         Text('Input an expense below!'),
         SizedBox(
@@ -81,8 +93,6 @@ class _MainAppState extends State<MainApp> {
                 ),
             )),
       ]),
-        ),
-      ),
     );
   }
 }