diff --git a/aio/content/examples/animations/src/app/hero.ts b/aio/content/examples/animations/src/app/hero.ts
index e3eac516da..a61b497759 100644
--- a/aio/content/examples/animations/src/app/hero.ts
+++ b/aio/content/examples/animations/src/app/hero.ts
@@ -1,4 +1,4 @@
-export class Hero {
+export interface Hero {
   id: number;
   name: string;
 }
diff --git a/aio/content/examples/architecture/e2e/src/app.e2e-spec.ts b/aio/content/examples/architecture/e2e/src/app.e2e-spec.ts
index 6dbc6952b8..d6e9316e8e 100644
--- a/aio/content/examples/architecture/e2e/src/app.e2e-spec.ts
+++ b/aio/content/examples/architecture/e2e/src/app.e2e-spec.ts
@@ -4,7 +4,7 @@ import { protractor, browser, element, by, ElementFinder } from 'protractor';
 
 const nameSuffix = 'X';
 
-class Hero {
+interface Hero {
   id: number;
   name: string;
 }
diff --git a/aio/content/examples/component-interaction/src/app/hero.ts b/aio/content/examples/component-interaction/src/app/hero.ts
index 3e80ad51c2..676f2e23b4 100644
--- a/aio/content/examples/component-interaction/src/app/hero.ts
+++ b/aio/content/examples/component-interaction/src/app/hero.ts
@@ -1,4 +1,4 @@
-export class Hero {
+export interface Hero {
   name: string;
 }
 
diff --git a/aio/content/examples/dependency-injection/src/app/heroes/hero.ts b/aio/content/examples/dependency-injection/src/app/heroes/hero.ts
index 5c49328241..1128cf6be2 100644
--- a/aio/content/examples/dependency-injection/src/app/heroes/hero.ts
+++ b/aio/content/examples/dependency-injection/src/app/heroes/hero.ts
@@ -1,6 +1,6 @@
 // #docregion
-export class Hero {
+export interface Hero {
   id: number;
   name: string;
-  isSecret = false;
+  isSecret: boolean;
 }
diff --git a/aio/content/examples/docs-style-guide/src/app/hero.ts b/aio/content/examples/docs-style-guide/src/app/hero.ts
index e1fc2f4fa9..e76ad2b900 100644
--- a/aio/content/examples/docs-style-guide/src/app/hero.ts
+++ b/aio/content/examples/docs-style-guide/src/app/hero.ts
@@ -1,4 +1,4 @@
-export class Hero {
+export interface Hero {
   id: number;
   name: string;
 }
diff --git a/aio/content/examples/hierarchical-dependency-injection/src/app/hero.ts b/aio/content/examples/hierarchical-dependency-injection/src/app/hero.ts
index 4ad6ccd8eb..9f05cb6cff 100644
--- a/aio/content/examples/hierarchical-dependency-injection/src/app/hero.ts
+++ b/aio/content/examples/hierarchical-dependency-injection/src/app/hero.ts
@@ -1,6 +1,6 @@
 // #docregion
 
-export class Hero {
+export interface Hero {
   id:   number;
   name: string;
   tid:  string; // tax id
diff --git a/aio/content/examples/ngcontainer/src/app/hero.ts b/aio/content/examples/ngcontainer/src/app/hero.ts
index 8619853380..5eafdef334 100644
--- a/aio/content/examples/ngcontainer/src/app/hero.ts
+++ b/aio/content/examples/ngcontainer/src/app/hero.ts
@@ -1,5 +1,5 @@
 // #docregion
-export class Hero {
+export interface Hero {
   id: number;
   name: string;
   emotion?: string;
diff --git a/aio/content/examples/router/src/app/heroes/hero.ts b/aio/content/examples/router/src/app/heroes/hero.ts
index e3eac516da..a61b497759 100644
--- a/aio/content/examples/router/src/app/heroes/hero.ts
+++ b/aio/content/examples/router/src/app/heroes/hero.ts
@@ -1,4 +1,4 @@
-export class Hero {
+export interface Hero {
   id: number;
   name: string;
 }
diff --git a/aio/content/examples/structural-directives/src/app/hero.ts b/aio/content/examples/structural-directives/src/app/hero.ts
index 4056351495..77f698e590 100644
--- a/aio/content/examples/structural-directives/src/app/hero.ts
+++ b/aio/content/examples/structural-directives/src/app/hero.ts
@@ -1,5 +1,5 @@
 // #docregion
-export class Hero {
+export interface Hero {
   id: number;
   name: string;
   emotion?: string;
diff --git a/aio/content/examples/styleguide/src/01-01/app/heroes/hero.component.avoid.ts b/aio/content/examples/styleguide/src/01-01/app/heroes/hero.component.avoid.ts
index 7e0775b858..d0cc29cf3f 100644
--- a/aio/content/examples/styleguide/src/01-01/app/heroes/hero.component.avoid.ts
+++ b/aio/content/examples/styleguide/src/01-01/app/heroes/hero.component.avoid.ts
@@ -4,7 +4,7 @@ import { Component, NgModule, OnInit } from '@angular/core';
 import { BrowserModule } from '@angular/platform-browser';
 import { platformBrowserDynamic } from '@angular/platform-browser-dynamic';
 
-class Hero {
+interface Hero {
   id: number;
   name: string;
 }
diff --git a/aio/content/examples/styleguide/src/01-01/app/heroes/shared/hero.model.ts b/aio/content/examples/styleguide/src/01-01/app/heroes/shared/hero.model.ts
index 8f7cc205c8..2b89781da5 100644
--- a/aio/content/examples/styleguide/src/01-01/app/heroes/shared/hero.model.ts
+++ b/aio/content/examples/styleguide/src/01-01/app/heroes/shared/hero.model.ts
@@ -1,5 +1,5 @@
 // #docregion
-export class Hero {
+export interface Hero {
   id: number;
   name: string;
 }
diff --git a/aio/content/examples/styleguide/src/03-03/app/core/hero.model.ts b/aio/content/examples/styleguide/src/03-03/app/core/hero.model.ts
index c3277621cb..fab0d4cb97 100644
--- a/aio/content/examples/styleguide/src/03-03/app/core/hero.model.ts
+++ b/aio/content/examples/styleguide/src/03-03/app/core/hero.model.ts
@@ -1,6 +1,6 @@
 // #docregion
 // #docregion example
-export class Hero {
+export interface Hero {
   name: string;
   power: string;
 }
diff --git a/aio/content/examples/styleguide/src/03-06/app/heroes/shared/hero.model.ts b/aio/content/examples/styleguide/src/03-06/app/heroes/shared/hero.model.ts
index c3277621cb..fab0d4cb97 100644
--- a/aio/content/examples/styleguide/src/03-06/app/heroes/shared/hero.model.ts
+++ b/aio/content/examples/styleguide/src/03-06/app/heroes/shared/hero.model.ts
@@ -1,6 +1,6 @@
 // #docregion
 // #docregion example
-export class Hero {
+export interface Hero {
   name: string;
   power: string;
 }
diff --git a/aio/content/examples/styleguide/src/05-04/app/heroes/shared/hero.model.ts b/aio/content/examples/styleguide/src/05-04/app/heroes/shared/hero.model.ts
index 8f7cc205c8..2b89781da5 100644
--- a/aio/content/examples/styleguide/src/05-04/app/heroes/shared/hero.model.ts
+++ b/aio/content/examples/styleguide/src/05-04/app/heroes/shared/hero.model.ts
@@ -1,5 +1,5 @@
 // #docregion
-export class Hero {
+export interface Hero {
   id: number;
   name: string;
 }
diff --git a/aio/content/examples/styleguide/src/05-15/app/heroes/shared/hero.model.ts b/aio/content/examples/styleguide/src/05-15/app/heroes/shared/hero.model.ts
index 8f7cc205c8..2b89781da5 100644
--- a/aio/content/examples/styleguide/src/05-15/app/heroes/shared/hero.model.ts
+++ b/aio/content/examples/styleguide/src/05-15/app/heroes/shared/hero.model.ts
@@ -1,5 +1,5 @@
 // #docregion
-export class Hero {
+export interface Hero {
   id: number;
   name: string;
 }
diff --git a/aio/content/examples/styleguide/src/05-17/app/heroes/shared/hero.model.ts b/aio/content/examples/styleguide/src/05-17/app/heroes/shared/hero.model.ts
index 8f7cc205c8..2b89781da5 100644
--- a/aio/content/examples/styleguide/src/05-17/app/heroes/shared/hero.model.ts
+++ b/aio/content/examples/styleguide/src/05-17/app/heroes/shared/hero.model.ts
@@ -1,5 +1,5 @@
 // #docregion
-export class Hero {
+export interface Hero {
   id: number;
   name: string;
 }
diff --git a/aio/content/examples/styleguide/src/07-01/app/heroes/shared/hero.model.ts b/aio/content/examples/styleguide/src/07-01/app/heroes/shared/hero.model.ts
index 8f7cc205c8..2b89781da5 100644
--- a/aio/content/examples/styleguide/src/07-01/app/heroes/shared/hero.model.ts
+++ b/aio/content/examples/styleguide/src/07-01/app/heroes/shared/hero.model.ts
@@ -1,5 +1,5 @@
 // #docregion
-export class Hero {
+export interface Hero {
   id: number;
   name: string;
 }
diff --git a/aio/content/examples/styleguide/src/07-03/app/heroes/shared/hero.model.ts b/aio/content/examples/styleguide/src/07-03/app/heroes/shared/hero.model.ts
index 8f7cc205c8..2b89781da5 100644
--- a/aio/content/examples/styleguide/src/07-03/app/heroes/shared/hero.model.ts
+++ b/aio/content/examples/styleguide/src/07-03/app/heroes/shared/hero.model.ts
@@ -1,5 +1,5 @@
 // #docregion
-export class Hero {
+export interface Hero {
   id: number;
   name: string;
 }
diff --git a/aio/content/examples/styleguide/src/07-04/app/heroes/shared/hero.model.ts b/aio/content/examples/styleguide/src/07-04/app/heroes/shared/hero.model.ts
index 8f7cc205c8..2b89781da5 100644
--- a/aio/content/examples/styleguide/src/07-04/app/heroes/shared/hero.model.ts
+++ b/aio/content/examples/styleguide/src/07-04/app/heroes/shared/hero.model.ts
@@ -1,5 +1,5 @@
 // #docregion
-export class Hero {
+export interface Hero {
   id: number;
   name: string;
 }
diff --git a/aio/content/examples/testing/src/app/demo/demo.ts b/aio/content/examples/testing/src/app/demo/demo.ts
index 72c8a80689..bbf1d8a799 100644
--- a/aio/content/examples/testing/src/app/demo/demo.ts
+++ b/aio/content/examples/testing/src/app/demo/demo.ts
@@ -11,7 +11,7 @@ import { delay } from 'rxjs/operators';
 
 ////////// The App: Services and Components for the tests. //////////////
 
-export class Hero {
+export interface Hero {
   name: string;
 }
 
diff --git a/aio/content/examples/toh-pt1/src/app/hero.ts b/aio/content/examples/toh-pt1/src/app/hero.ts
index e3eac516da..a61b497759 100644
--- a/aio/content/examples/toh-pt1/src/app/hero.ts
+++ b/aio/content/examples/toh-pt1/src/app/hero.ts
@@ -1,4 +1,4 @@
-export class Hero {
+export interface Hero {
   id: number;
   name: string;
 }
diff --git a/aio/content/examples/toh-pt2/src/app/hero.ts b/aio/content/examples/toh-pt2/src/app/hero.ts
index e3eac516da..a61b497759 100644
--- a/aio/content/examples/toh-pt2/src/app/hero.ts
+++ b/aio/content/examples/toh-pt2/src/app/hero.ts
@@ -1,4 +1,4 @@
-export class Hero {
+export interface Hero {
   id: number;
   name: string;
 }
diff --git a/aio/content/examples/toh-pt3/src/app/hero.ts b/aio/content/examples/toh-pt3/src/app/hero.ts
index 8f7cc205c8..2b89781da5 100644
--- a/aio/content/examples/toh-pt3/src/app/hero.ts
+++ b/aio/content/examples/toh-pt3/src/app/hero.ts
@@ -1,5 +1,5 @@
 // #docregion
-export class Hero {
+export interface Hero {
   id: number;
   name: string;
 }
diff --git a/aio/content/examples/toh-pt4/src/app/hero.ts b/aio/content/examples/toh-pt4/src/app/hero.ts
index e3eac516da..a61b497759 100644
--- a/aio/content/examples/toh-pt4/src/app/hero.ts
+++ b/aio/content/examples/toh-pt4/src/app/hero.ts
@@ -1,4 +1,4 @@
-export class Hero {
+export interface Hero {
   id: number;
   name: string;
 }
diff --git a/aio/content/examples/toh-pt5/src/app/hero.ts b/aio/content/examples/toh-pt5/src/app/hero.ts
index e3eac516da..a61b497759 100644
--- a/aio/content/examples/toh-pt5/src/app/hero.ts
+++ b/aio/content/examples/toh-pt5/src/app/hero.ts
@@ -1,4 +1,4 @@
-export class Hero {
+export interface Hero {
   id: number;
   name: string;
 }
diff --git a/aio/content/examples/toh-pt6/src/app/hero.ts b/aio/content/examples/toh-pt6/src/app/hero.ts
index e3eac516da..a61b497759 100644
--- a/aio/content/examples/toh-pt6/src/app/hero.ts
+++ b/aio/content/examples/toh-pt6/src/app/hero.ts
@@ -1,4 +1,4 @@
-export class Hero {
+export interface Hero {
   id: number;
   name: string;
 }
diff --git a/aio/content/examples/universal/src/app/hero.ts b/aio/content/examples/universal/src/app/hero.ts
index e3eac516da..a61b497759 100644
--- a/aio/content/examples/universal/src/app/hero.ts
+++ b/aio/content/examples/universal/src/app/hero.ts
@@ -1,4 +1,4 @@
-export class Hero {
+export interface Hero {
   id: number;
   name: string;
 }