AngularJS - While using filter with ng-repeat to display checkboxes, they get unchecked

I'm planning on displaying a lot of checkboxes to the user so I tried implementing a filter option where the user can search for a specific item they would like to select. I display the list of checkboex with the ng-repeat directive and filter the results based on what the user types.

The problem is that if an option, already checked, gets filtered out, it gets unchecked. How do I prevent this from happening? This is the relevant code

verbSelect.html

<div class="row">
    <div class="col-xs-12">
        <h3>Select the verbs</h3>
        <input type="text" ng-model="filterText" />
    </div>
    <div class="col-xs-12">
        <span ng-repeat="verb in verbArray | filter: filterText">
            <label class="checkbox" for="">
                <input type="checkbox"/><img src=""/>
            </label>
        </span>
    </div>
</div>

The above code is under this controller:

.controller('verbController', ['$scope', 'verbFactory', function($scope, verbFactory){
    //Gets verbs from server
    $scope.verbArray = verbFactory.getVerbs().query(
        function(response) {
            $scope.verbArray = response;
        },
        function(response) {
            $scope.message = "Error: " + response.status + " " + response.statusText;
        }
    );

    //Sotres the array of selected verbs
    $scope.selectedVerbs = {};

    //Stores how many practice questions the user wants
    $scope.howMany = 0;

    //Stores what tense of verbs the user wants
    $scope.verbTense = "both";

    //Stores what form the user wants
    $scop.verbVoice = "both"

    //Include commands?
    $scope.includeCommands = true;

}])