If you get this type of following errors :
Can't bind to 'ngModel' since it isn't a known property of 'input' ”
You just import the FormsModule in your's module file and also add the reference in imports array so that you can not get this type of error again
import { NgModule } from '@angular/core';
import { FormsModule } from '@angular/forms';
import { AppComponent } from './app.component';
import { SimpleComponent } from './simple/simple.component';
@NgModule({
  declarations: [
    AppComponent,
    SimpleComponent
  ],
  imports: [
    BrowserModule,
    FormsModule
  ],
  providers: [],
  bootstrap: [AppComponent]
})