Arbor Montessori School issued the following announcement on March 16.
More hands on science work in our elementary curriculum. The River Model is a physical, project-based representation of many abstract lessons. Children learn how rivers carve, carry, and deposit; what erosion by water looks like and how canyons and valleys are formed; and the importance of rivers to plants and animals and how they have been important to ancient civilizations and in the modern day. With these lessons, students can take abstract concepts and build their own models, showing off their newfound knowledge.
Original source can be found here.