The 4th Grade Performance Expectations (PEs) are organized into three bundles in this model. Each bundle is characterized by the overarching theme that students can find evidence of patterns and systems throughout the designed world. Each bundle also relates to energy transfer, as students begin to learn about the concept of energy in moving and colliding objects and the role of energy in a large system early in the year, and then can apply that knowledge to information transfer and to different Earth systems later in the year.