A-Class pages are comprehensive, intuitive, engaging, well-organized, and, where it would be useful, include excellent supporting material (e.g. examples, images, and exercises). You would enjoy learning from it, and send it to your friends. To reach A-Class pages must receive detailed feedback from both the target audience to make sure it's a good experience to learn from and reviewers with a strong understanding of the topic.
For higher level audiences asking on Slack is a good way to get feedback, for Math 0 or Math 1 sharing with your friends (in real life of via social media) is a better bet. To get the reviewers attention ask in #reviews on Slack.
A-Class pages are:
This tag should only be added by reviewers.