$('#edit-'+id+'-add').on( 'click', function() {
        var pair_add = $('<div id="edit-'+id+'-pair-'+words+'" class="word_pair">');
        $(pair_add).append('<input type="text" name="droppable[]"  id="edit-'+id+'-droppable-'+words+'" placeholder="kohde" required/>');
        $(pair_add).append('<input type="text" name="draggable[]"  id="edit-'+id+'-draggable-'+words+'" placeholder="vedettävä" required/>');
        $(pair_add).append('<input type="text" name="showable[]"  id="edit-'+id+'-showable-'+words+'" placeholder="näytettävä" required/>');