Another aspect of affordances is that AR superimposing virtual objects or information onto physical objects or environments enables
visualization of invisible concepts or events (Arvanitis et al., 2007; Dunleavy et al., 2009). AR systems could support learners in visualizing
abstract science concepts or unobservable phenomena, such as airflow or magnetic fields, by using virtual objects including molecules,
vectors, and symbols. For example, Augmented Chemistry allowed students to select chemical elements, compose into 3D molecular
models, and rotate the models (Fjeld & Voegtli, 2002). Clark, Dünser, and Grasset (2011) augmented a paper-based coloring book with 3D
content and provided children with a pop-up book experience of visualizing the book content. These augmented real objects create new
visualizations that have potential to enhance students’ understanding of abstract and invisible concepts or phenomena.