function changeHeadingA(){
	document.getElementById('heading').innerHTML = '<h1>learn about lizzy</h1>';}
function changeHeading0(){
	document.getElementById('heading').innerHTML = '<h1>pre-reading</h1>';}
function changeHeading1(){
	document.getElementById('heading').innerHTML = '<h1>level 1</h1>';}
function changeHeading2(){
	document.getElementById('heading').innerHTML = '<h1>level 2</h1>';}
function changeHeading3(){
	document.getElementById('heading').innerHTML = '<h1>level 3</h1>';}
function changeHeading4(){
	document.getElementById('heading').innerHTML = '<h1>level 4</h1>';}
function changeHeading9(){
	document.getElementById('heading').innerHTML = '<h1>Assessment</h1>';}