function toggleExplanation (elementStr) {
	var element;
	element = document.getElementById('explanation-'+elementStr);
	toggleDisplay(element);
	element = document.getElementById('arrow-'+elementStr);
	toggleArrow(element);
}

function toggleDisplay(element) {
		if (element.style.display=='none') {element.style.display='block';} else {element.style.display='none';};
}

function toggleArrow(element) {
		if (element.src.search('blue-arrow-right.png')>0) {element.src='images/blue-arrow-down.png';} else {element.src='images/blue-arrow-right.png';};
}