marvin, who lives in san francisco, has been asked to host a teenage alien, regor, as part of an intergalactic exchange program. marvin is sure that regor would love to experience the adventure of sailing, but decides he should introduce the concept of a "sailboat" first. after some time studying, regor has learned quite a bit about sailboats and is now excited about experiencing life on the water. so, marvin and his dad take regor sailing one weekend. regor now has a set of beliefs, expectations, and personal experiences related to sailboats and sailing to which he can add new information. this is called a