A nice way to improve your knowledge of some high school subjects!
Socratic is a good learning app for high school students. If you are stuck with a subject and there is too much of information and sources on the web, you can refer to the app: ask it a question and it will find the best resources to study most high school subjects, such as Algebra, Trigonometry, Geometry, Chemistry, Biology, History and Literature. The developers are planning on adding more subjects to the list.
The app is powered by Google AI and gives you the best learning materials. You can learn using step-by-step explanations and walkthroughs, video guides, lectures, podcasts, graphs and schemes developed in collaboration with high-school teachers and university professors to help you to figure out about any high school subject that you are not feeling sure about.
The Socratic app is also available for your iPhone and iPad. You can download it here.