Khan Academy PC is the official app for Android from the site of the same name, which aims to teach various educational content, targeted not only for students, but also for parents and teachers.
For you to understand the content, the service uses videos with objective explanations and captions to facilitate the understanding of what is said. Khan Academy is available only in English and therefore the subtitles are essential and quite useful, even if you’ve mastered the language.
The interface is divided into the following subjects: mathematics, Science, economics and finance, and arts and Humanities. Each of which is subdivided into subjects — in science, for example, you will find topics specific to biology, chemistry, physics, among others.
You can access each topic this way or use the search tool to easily find the app you want. Khan Academy even allows you to create a selection with your favorite videos and have the option to login, so that you create a user and see their performance in studies.