It is interesting that you mention your students' interests in the horseshoe crabs. Prior to this year, the 4th graders in PG County, had the opportunity to participate in the WSSC Water Festival. One of the activities of the festival, the students learn about the animals in the area that are affected by the water shed and climate change. There is a big focus on the horseshoe crab. Many of my students have not had any encounters with the animal, so it is an attention grabber for them.