3.select('#sortable');
  ul.html('');
  var n = 9;
  for(var i=0;i<n;i++) {
    var li = ul.append('li').attr('class', 'ui-state-default');
    li.append('div').html(ITEMS[i]);
  }

  var ix = core.randi(0,n) + 1; // ground truth item index, 1-indexed
  var poss = [];

  // positional options
  if (ix !== 1) { poss.push(['to the top left.', 1]); }
  if (ix !== 2) { poss.push(['to the top center.', 2]); }
  if (ix !== 3) { poss.push(['to the top right.', 3]); }
  if (ix !== 4) { poss.push(['to the center lef