if (document.images) {
	whatisOff = new Image
	whatisOn = new Image
	youOff = new Image
	youOn = new Image
	aboutOff = new Image
	aboutOn = new Image
	teacherOff = new Image
	teacherOn = new Image
	contactOff = new Image
	contactOn = new Image

	whatisOff.src = "images/whatis-off.gif"
	whatisOn.src = "images/whatis-on.gif"
	youOff.src = "images/you-off.gif"
	youOn.src = "images/you-on.gif"
	aboutOff.src = "images/about-off.gif"
	aboutOn.src = "images/about-on.gif"
	teacherOff.src = "images/teacher-off.gif"
	teacherOn.src = "images/teacher-on.gif"
	contactOff.src = "images/contact-off.gif"
	contactOn.src = "images/contact-on.gif"
}

function chgImg(imgField,newImg) {
	if (document.images) {
		document[imgField].src= eval(newImg + ".src")
	}
}