We're always working to improve and expand Khan Academy, including by adding more concepts to learn! One consequence of adding this new content is it can sometimes impact Mastery percentages. When we add new content, your Mastery percentage may go down, since the overall number of skills available will increase (for example, instead of mastering 90 out of 100 skills, you'll now have mastered 90 out of 110, which would reduce your percentage from 90% to 82%). You'll still have mastered the same number of skills as before, you'll just have additional ones to complete now. But don’t worry, this doesn’t affect Mastery points. Whenever there are updates to course content that could affect your Mastery percentage, you’ll see a “New content added!” notice in the course, with a link to this page. Here you’ll find more information on what specifically updated so you can better understand what’s changed in course content.
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