Jonny316,
<!DOCTYPE HTML>
<html>
<head>
<title>Untitled</title>
<meta charset="utf-8">
<style type="text/css">
.small {
width:100%;
height:50px;
background: pink;
}
.big {
width:100%;
height:100px;
background: green;
}
</style>
<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.11.0/jquery.min.js"></script>
<script type="text/javascript">
$(document).ready(function() {
$('.content').click(function() {
$('.content').not(this).removeClass('big').fadeToggle(1500);
$(this).toggleClass('big');
});
});
</script>
</head>
<body>
<div class='content small'>
БЛОК 1
</div>
<div class='content small'>
БЛОК 2
</div>
</body>
</html>