This is not a Word top tip but an Excel top tip. If you want to select a name at random from a class list in Excel, for example to ensure that you are randomising questions or asking students to read out loud, type this formula into a cell near the list:
=INDEX($A$2:$A$25,RANDBETWEEN(1,ROWS($A$2:$A$25)),1)
Every time you click on F9 (or Fn+F9) the cell will be populated by a name at random from the list.