Okay, so you know when you draw a picture or paint a picture and you do it right side up, like how you normally see things? Well, upside-down painting is when you turn the picture upside down and paint it that way!
It might seem silly or weird, but it actually helps artists see the picture in a different way. Sometimes, when we look at things too much one way, our brains get used to seeing it that way and we miss little details or things that don't quite look right. But when we flip the picture, it's like we're seeing it for the first time again, and we notice things we didn't see before.
So, when an artist paints a picture upside down, they are actually training their brains to look at things in a different way, which can help them become better artists. It's a fun and creative way to experiment and see things from a new perspective.