This three page worksheet set is a good way to introduce the concepts of positive and negative space. Although sometimes this concept is hard to visualize, this worksheet set uses a combination of fun illusions and free-form colouring to guide the student.
Using widely known double images, or optical illusions, students can separate two different areas of an image and look at them each as individual pieces.
Using selectively chosen colouring book style open-source images, students can pick out the areas in an image they feel contribute to the positive or negative space. This is a very relaxed exercise that lets the students explore the concept at their own pace with a familiar exercise.