Creating a very simple game in Pygame using classes and functions

Using Pygame and Python 3 (the version is important!), I would like the following 10 small programs (created separately and labelled 1..2..3..etc): What I require is a simple progression for children, to show creating a game from scratch. All code must be commented and made as simple as possible. Python File 1. Create a ball class with a simple sphere (ball1) on the screen (no movement) Python File 2. Create user key (up, down, left right arrow key) movement for the ball Python File 3. Add a score variable and add a smaller GREEN ball (ball2) (inherits from the ball class) that randomly moves about the screen. When ball1 touches the green ball, the score increments by +10. Python File 4. Create a red ball (ball 3) When ball 1 touches the red ball, the score decrements by -10. Python File 5. Add a "Game over" feature. When the score reaches 1000 (You Win) or when the score reaches -1000 (You lose)