function ShowHideLesson(selectedCat){
	// Show selected
	h = document.getElementById(selectedCat+'Content');
	hStyle = h.style.display;
	img = document.getElementById(selectedCat);
	if (hStyle=='block') {
		h.style.display = 'none';
		img.src = 'images/arrow0_right.gif';
	} else {
		h.style.display = 'block';
		img.src = 'images/arrow0_down.gif';
	}
}