MIT OpenCourseWare is like a big library full of really cool videos, pictures, and articles that you can read and learn from! It's like a magic place where you can study everything from math and science, to painting and music, from some of the smartest people in the world - the teachers at the Massachusetts Institute of Technology (MIT)!
All the grown-up teachers at MIT have been very kind and made all their teaching materials available for free, so you can learn just like the students do - by watching videos of real lessons, doing quizzes, and reading articles. This way, you can learn all kinds of things about the world around you and how things work, just by logging in to the internet and clicking a button!
So if you ever want to learn something new or understand a subject better, just head on over to MIT OpenCourseWare - it's like a treasure trove of knowledge, just waiting for you to explore and learn from!