I have been doing this lesson for years and the results are always different. First graders were instructed to draw hearts of varying sizes and patterns on their papers.
Once they finished the drawings, we talked about how to create tints-add white to a color; shades-add black to a color and tones-add gray to a color. They used red paint to create the tints, shades and tones. Using the newly created colors, they filled in their hearts.