Add schema information to WordPress loop

single.php

<div itemscope itemtype="http://schema.org/Article" class="content">

<h1 itemprop="name"><?php the_title(); ?></h1>

<div class="entry-content">
  <?php
	if ( has_post_thumbnail() )
		the_post_thumbnail( 'single-post-thumbnail', array( 'itemprop' => 'image' ) );
	else
		echo '<img src="' . get_bloginfo( 'stylesheet_directory' ) . '/images/default_thumb1.jpg" class="attachment wp-post-image" />';
  ?>
  <?php if( strpos(get_the_content(), '<span id="more-') ) : ?>
	<div class="postintro" itemprop="description">
	<?php global $more; $more=0; the_content(''); $more=1; ?>
	</div>
  <?php endif; ?>
  <?php the_content('', true); ?>

</div><!-- .entry-content -->
</div><!-- .content -->

Why not filter the post class

This is from 11 years ago, so I wouldn't really worry about it :)