title: mat-checkbox and ngIf in angular 5 is not working
body: <p>I have this code to hide and show a piece of content every time a checkbox is ticked and unticked. However, it is not working.</p>
  
  <pre><code>&lt;mat-checkbox ngModel="checked" ngInit="checked=true"&gt;Check me!&lt;/mat-checkbox&gt;
              &lt;div *ngIf="checked"&gt;
                      &lt;mat-radio-group formControlName="contactSupport"&gt;
                              &lt;mat-radio-button value="Low"&gt;Low&lt;/mat-radio-button&gt;
                              &lt;mat-radio-button value="Normal"&gt;Normal&lt;/mat-radio-button&gt;
                              &lt;mat-radio-button value="high"&gt;high&lt;/mat-radio-button&gt;
                              &lt;mat-radio-button value="none"&gt;None&lt;/mat-radio-button&gt;
                      &lt;/mat-radio-group&gt;
  
              &lt;/div&gt; 
  </code></pre>