I have just finished a great lesson with my first graders. They learned about cityscapes, by creating a crayon resist painting, using crayons and watercolors.
We started by folding the paper in half horizontally, and drew an outline of a cityscape on the top half of the paper. The students pressed hard with their crayons, so that they can transfer the drawing onto the bottom half of the paper by refolding the paper, and rubbing it with something hard (we used the handles of our scissors). The transferred image is light, so the student trace over it with their crayons, and then color in their buildings, again pressing hard. Once the buildings are colored in , the student paint one side of their paper with blue watercolors, and the other side black. This way, they have a night and day picture.