The Open University in America has a free home study program called Open Learn. The program has over 800 courses on subjects such as money management, astronomy and even managing a football club. ALISON, another resource for free home study courses offers courses on language, technology and many more.
The Open Learn program has a popular free home study course on the moons in the solar system. A prior knowledge of astronomy is not required to take this course. Among other things, the course teaches about the origin and diversity of moons, the surfaces and interior layers of the moon, how craters are formed and the historical, current and future explorations of the moons.
ALISON has more than 750 free courses with either a diploma or certificate at the end of them. The courses are divided into nine different categories such as diploma courses, IT skills and digital literacy, health and safety and so on. This makes it easy for a student to select a category of their interest and select a subject or topic under that category. This resource also offers courses drawn from school syllabi. This includes subjects such as math, chemistry, technology, basic and advanced biology and advanced physics. There are a total of 83 courses just under this category.