This is a simple but effective art lesson that I have used for many themes.
One year, I used photos I had taken with the children during a local trail and the children added in the details they remembered to complete the picture.
I print out a picture or photo for the children and stick it on the page.
They use their imagination to complete their work of art. At the end I ask the children to chose a title for their art.
Sometimes I use pastels or colouring pencils but just using pencils can also create a nice contrast.