node_modules/material-design-lite/src/checkbox/snippets/check-on.html

<label class="mdl-checkbox mdl-js-checkbox mdl-js-ripple-effect" for="checkbox-1">
  <input type="checkbox" id="checkbox-1" class="mdl-checkbox__input" checked>
  <span class="mdl-checkbox__label">Checkbox</span>
</label>