<style>
.under{
display:none;
padding:5px;
background-color:gray;
}
</style>
<div class="section" id="1">Hi</div>
<div class="under" id="1">Hola</div>
<div class="section" id="2">Foo bar</div>
<div class="under" id="2">Derp</div>
<script>
$(".section").click(function(){
$(this).next('div').slideToggle("slow");
});
</script>