Positive Negative, Second Grade
I've done this lesson every year with second grade. Each student takes a 12 x 18 piece of construction paper and a stack of 6" x 4.5" black paper. The black paper is folded in half, then a design is cut. The student then cuts down the fold and glues the positive shape down, then its negative. It takes some students a few tries but the others who grasp it quickly always help out.