this is a wonderful idea. When i was a kid i alway had a hard time telling the difference in clouds with out looking at a text book love love love this! Cloud inspector (science for kids, weather activity)
Water wall is another way for kids to explore water flow.
"Textured Painting - Natures Paint Brushes" This is not just art, but art in nature! Go on a nature walk to gather 'schtuff!' Then use what you gather to create art or As art!
5 Fun Ways to Paint in the Rain (Art, rain, paint)
Tossing the leaves into the air - love this - would add little rakes so that they could rake the leaves into a pile and then put them on the parachute.