I started by cutting several sizes of the different shapes I was doing and then let them glue a city or an ocean.
Then they went at it, giggling at the shapes they had picked.
Here they are all finished - minus 2 that were too wet to hang.
I added faces and a tag with name, date, title of project.
Cute and colorful! :)
If you wanted to make this more advanced you could trace shapes and have them cut them out themselves.