If any one is looking for outdoor art activities I can highly recommend the Wooland Trusts Nature Detectives. There are free art ideas and activities for children to do this summer. You don't have to be a member. When my GCs are old enough I will enrol them ( they have to be 5, I think). I have used this resource for many years whilst working with young adults with learning difficulties it is aimed at children from 5 to 12. There are recipes, spotter sheets and colouring sheets and lots of good ideas to try out.
Thanks GCornwall I have just looked at the site. There are some very useful ideas for outdoor activities for children. My five year old granddaughter fancies worm charming and snail racing next week so two afternoons sorted.
My DGC have started making fairy houses wherever they go. They are great fun - you just let your imagination roam free whilst out on a country walk and create a home for the little people from sticks, berries, leaves, acorn cups etc. The joy is knowing that someone else will come across it and be charmed and surprised by it. My SIL takes a small saw out with him to help this project.
Some people make incredibly elaborate homes with staircases etc.