I haven't had this kind of conversation since I was 8 and arguing with my 6 year old sister.
How exactly do you think we get facts?
Because we either gather them through observation of the world around us or make them up in our heads.
Seeing the ball is green, one time, and saying that is a "fact" is making things up in your head.
Take the ball to another room, it's yellow. Take it back, it's green. Huh, observation just proved that the ball is NOT green. Take the ball and the light to another room, the ball is now green. Increasing our knowledge base. If we keep gathering knowledge, we will eventually find that the ball IS yellow (fact) and the blue light makes it look green (fact). From that point, those two facts have been set. No other observations will change that, so you cannot,
make them up in our heads
that the ball is red ... and suddenly change the fact that the ball is yellow!!!
Observations REVEAL the facts ... they don't CREATE them.
evidence over faith ... observation over theory