New Twiddle

components.my-child.js

import Ember from 'ember';

export default Ember.Component.extend({
  classNameBindings: ['isSelected:addBorder'],
  
  isSelected: Ember.computed('item', 'selectedItemTitle', function () {
    return this.get('item') === this.get('selectedItemTitle');
  })
});

components.my-parent.js

import Ember from 'ember';

export default Ember.Component.extend({
  selectedItemTitle: null,
  
  actions: {
  	selectItem(item) {
      this.set('selectedItemTitle', item);
    }
  }
});

controllers.application.js

import Ember from 'ember';

export default Ember.Controller.extend({
  appName: 'Ember Twiddle'
});

routes.index.js

import Ember from 'ember';

export default Ember.Route.extend({
  model(){
  	return [
      {title:"Mango",info:"mango is yellow"},
      {title:"Lotus",info:"Lotus is flower and white"},
      {title:"Lilly",info:"Lilly as well flower but rose color"}
    ];
  }
});

styles.app.css

body {
  margin: 12px 16px;
  font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif;
  font-size: 12pt;
}

ul,li{
padding:0;
  margin:0;
}

li{
  background:lightgray
}

.addBorder{
border:1px solid green;
}

templates.application.hbs

<h1>Welcome to {{appName}}</h1>
<br>
<br>
{{outlet}}
<br>
<br>

templates.components.my-child.hbs

<div class="wrap">
	<h5>{{item}}</h5>
  <p>{{info}}</p>
</div> 

templates.components.my-parent.hbs

<h2 class="addBorder">On click list will be highlighed like me</h2>
<ul>
	{{#each model as |item|}}
  	{{my-child item=item.title info=item.info tagName="li" selectedItemTitle=selectedItemTitle click=(action 'selectItem' item.title)
    }}
  {{/each}}
</ul> 

templates.index.hbs

<h1>I am from Index page </h1>
{{my-parent model=model}}

twiddle.json

{
  "version": "0.12.1",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/1.11.3/jquery.js",
    "ember": "2.12.0",
    "ember-template-compiler": "2.12.0",
    "ember-testing": "2.12.0"
  },
  "addons": {
    "ember-data": "2.12.1"
  }
}