img1 = new Image();
img1.src = "images/b_home_off.gif";
img1on = new Image();
img1on.src = "images/b_home_on.gif";

img2 = new Image();
img2.src = "images/b_schedule_off.gif";
img2on = new Image();
img2on.src = "images/b_schedule_on.gif";

img3 = new Image();
img3.src = "images/b_about_off.gif";
img3on = new Image();
img3on.src = "images/b_about_on.gif";

img4 = new Image();
img4.src = "images/b_students_off.gif";
img4on = new Image();
img4on.src = "images/b_students_on.gif";

img5 = new Image();
img5.src = "images/b_contact_off.gif";
img5on = new Image();
img5on.src = "images/b_contact_on.gif";

function on(name) {document[name].src = eval(name + "on.src");}
function off(name) {document[name].src = eval(name + ".src");}