Edit in JSFiddle

<div ng-app="myApp" ng-controller="mainController">
    Parent: {{person.name}}
    <div ng-controller="nestedController">
        Nested: {{person.name}}
        <input ng-model="person.name" />
    </div>
</div>
var app = angular.module('myApp', []);

app.controller('mainController', ['$scope', function($scope) {
    $scope.person = {name: "David"};
}]);

app.controller('nestedController', ['$scope', function($scope) {
    
}]);