Select one of your Google Classroom™ classes and create a Leaderboard in the document. You have the options to set the leaderboard size, points multipliers (or not show points at all), add the leaderboard as a text post in Google Classroom™, and schedule the leaderboard to update after set times. Once your Leaderboard is ready, publish the document to the web and share the url, or embed the published HTML page in a google site.