function GetTip()
  {

//create array of facts
var facts = new Array();
facts[0] = "The Great Lakes contain nearly 20% of the world's surface freshwater and 95% of the U.S.'s fresh surface water.";
facts[1] = "The Great Lakes are the economic engine of the region. 40% of the Canadian and 15% of the US Gross Domestic Product originates within the basin.";
facts[2] = "56 billion gallons (210 billion liters) of water are used each day for municipal, agricultural, and industrial uses.";
facts[3] = "The 10,000 mile (17,000 kilometer) coastline is longer than that of the U.S. Pacific and Atlantic coasts combined.";
facts[4] = "The Great Lakes hosts the world's largest collection of freshwater sand dunes in the world.";
facts[5] = "More than 217,000 hectares (534,000 acres) of coastal wetlands are found throughout the Great Lakes including the St. Clair Delta, the largest freshwater delta in the world.";
facts[6] = "More than 3,500 species of plants and animals inhabit the Great Lakes basin.";

//random number between 0 and n-1, where n is the number of items in the array
var randomnumber = Math.floor(Math.random() * facts.length);
//get random fact
var facttext = facts[randomnumber];
//update html with fact text
document.getElementById('facttext').innerHTML = facttext;
  }