title: How to make a check_box checked in rails?
body: <p>I made checkboxes using the following rails form helper:</p>
  
  <pre><code>&lt;%= check_box("tag", tag.id) %&gt;
  </code></pre>
  
  <p>However, I need to make some of them checked by default.  The rails documentation doesn't specify how to do this.  Is there a way?  How?</p>