Marion Underwood
... that developmental researcher Marion Underwood found that a group of ninth-grade students sent an average of 1,321 text messages a month?
... that developmental researcher <b id="mwAlk"><a href="./Marion_Underwood" id="mwAlo" rel="mw:WikiLink" title="Marion Underwood">Marion Underwood</a></b> found that a group of <a href="./Ninth_grade" id="mwAls" rel="mw:WikiLink" title="Ninth grade">ninth-grade</a> students sent an average of 1,321 <a href="./Text_messaging" id="mwAlw" rel="mw:WikiLink" title="Text messaging">text messages</a> a month?