You could start by examining the curriculum of popular schools in your city, to understand what are the various modules / lessons/ where making video lectures would help.
Video Lectures are a bit of a monologue, so unless one is an absolute expert , i think an interactive mechanism is more viable, when dealing with students. The obvious place where technology can really help in the education field is in making concepts clear to students which are otherwise difficult to understand eg- Ohms Law in Physics, Vulcanization of Rubber in Chemistry, GreenHouse Effect in Environmental Science, The Role of Gravity Curved Space and Time in AstroPhysics, etc to name a few. These mentioned subjects are largely learnt in our childhood by memorization without actually understanding the underlying fundamental concepts.
In my first stint at a creative agency in 2003, i got the opportunity to make Macromedia Flash Based -Computer Based Tutorials for a leading MATLAB training provider, and we used to simulate various computational processes at the microprocessor level . Though painstaking it was revenue generating for the small company that i was working for.
As far as Quizzes go, you can get a tablet based quiz software created with a provision for question bank database and you can sell the same to educational institutions. Most schools have some screening process for selecting students to courses, and they can use your quiz software for screening purposes as well, not to mention actual Quiz Programs.
These are just ideas, and the fundamental reason why entrepreneur'ial ideas abound in the ecosystem but very few go on to become successful is very simple - It is difficult to get people who are willing to sweat it out , go to schools, teachers (target audience) , figure out the market potential ,come up with some actual numbers and make a slide deck.
Once all this is ready, its just a matter of pitching ideas to potential investors in the education space. Here is an interesting article on the edtech space in India
India’s ‘Ed-tech’ Startups Face Opportunities – and a Few Challenges
All the best.