尝试一下

 <select id="cd-dropdown" name="cd-dropdown" class="cd-select">
   <option value="-1" selected>choose an option to test</option>
   <option value="1" class="icon-monkey">Students</option>
   <option value="2" class="icon-bear">Courses</option>
   <option value="3" class="icon-squirrel">Instructors</option>
   <option value="4" class="icon-elephant">Departments</option> 
</select>

<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script>
<script type="text/javascript">

    jQuery('#cd-dropdown').on('change', function(){
        if(jQuery(this).val() == 1){
        window.location.href = 'http://google.com'
        }
        // and so on
        })
</script>

您必须为所有选项jQuery代码提供目标URL.

You have to give the destination URL for all options jQuery code.