HRI researchers, in collaboration with content experts, identified multiple primary phenomena for each sub-idea of the three content areas (Flow of Matter & Energy, Force & Motion, and Plate Tectonics). In Flow of Matter and Energy and Plate Tectonics, each primary phenomenon has one or more associated evidentiary phenomenon. (All of primary phenomena for Force and Motion were directly observable; therefore, there were no evidentiary phenomena.) The multi-faceted matrix approach required the rating of each evidentiary phenomenon on several dimensions to arrive at a series of aggregate scores that represented student opportunity to learn. An example matrix for one Plate Tectonics evidentiary phenomenon shows the combination of criteria that were applied.