open_in_new content_copy 
<style>
.wrapper {
  display: flex;
  flex-direction: column
}

@media only screen and (max-width: 767px) {
  .wrapper1 {
    order: 2
  }
  .wrapper2 {
    order: 1
  }
}
</style>

<body>
  <div class="wrapper">
    <div class="wrapper1">
      <div class="col s12 l6">
        some text
      </div>
    </div>
    <div class="wrapper2">
      <div class="col s12 l6">
        some more text
      </div>
    </div>
  </div>
</body>