My second grade did this line project using the crayon resist technique.  I painted the boards with the thick black lines and each team of students was given a board to use crayons to draw “The Lines of Design” (some were using color pencils) on the white space.  Once the boards were all filled with lines.  They used watercolor to paint the boards and watch their lines pop through the paint like magic.  I then put all the boards together to create a mural for the Art Exhibition.