function preloadImages() {
	var volunteer = new Image
		volunteer.src = "images/volunteer-over.gif"
	var becomemember = new Image
		becomemember.src = "images/becomemember-over.gif"
	var whoweare = new Image
		whoweare.src = "images/whoweare-over.gif"
	var visitus = new Image
		visitus.src = "images/visitus-over.gif"
	var explore = new Image
		explore.src = "images/explore-over.gif"
	var dohistory = new Image
		dohistory.src = "images/dohistory-over.gif"
	var forteachers = new Image
		forteachers.src = "images/forteachers-over.gif"
	var getinvolved = new Image
		getinvolved.src = "images/getinvolved-over.gif"
	var jobs = new Image
		jobs.src = "images/jobs-over.gif"
}

window.onload = preloadImages;

function changeImages(sName,sImage) {
  document.images[sName].src = sImage
}