This piece was created 100% by my 4 year old little girl. After asking for a bunch of materials, my little girl explained what she wanted to do and it blew me away. She explained how she wanted to make a picture with Cacti and that they would big, middle and small.
She explained "The big would be more colourful and be closer to you, the middle will look pretty and be further back and the small ones are far away with less colour"
My 4 year old is already talking about depth in art :o, my wife and I are very proud of her.