What Will Happen Next?

I wrote a little book in grade four called "What Will Happen next?" It is a story written in the second person (I was really into choose your own adventure books at the time) about a scientist (you) who is tring to make a shrinking potion. You succeed but accidentally spill it on yourself instead of your intended guinea pig and shrink. You decide that you are too small to get back up on your lab table to do anything about it and go to sleep in a mouse hole. After waking up and nearly being eaten by the mouse you find the strength to make your way to the top of the lab table. You then make and drink a growth potion and grow to be eight feet six inches tall. You then become a basketball player. I hope I don't need to explain the significance of all this. How did I know how it was going to go when I was only nine years old?