While observation is critical to science, sometimes things cannot be observed directly. Sometimes things happened long ago (in paleontology, for example) or are too small to observe (like atoms). Many students believe that science progresses only through direct observation. Students may also believe that giant microscopes provide insight into atoms, for example. This lesson can introduce students to the small world and how it is studied. In this lesson, students roll marbles under a cardboard and block setup to determine the shape hidden underneath. This lesson can fit into a number of different contexts. It can work in a larger unit on matter for older elementary children (fifth and sixth grades) or be used to enhance a unit on models and design. For younger children, it provides insight into how scientists work