Edit in JSFiddle

$('#check').click(function() {
    $("#box").slideToggle(this.checked);
});
  
  

input{margin:80px 0 0 80px;}
div{
    display:none;
    margin:25px;
    padding:25px;
    background:#eee;
    width:200px;
    height:150px;
}

<label><input type="checkbox" id="check">Check This!</label>
<div id="box">content is here</div>