You may want to consider researching estuary animals, plants, locations, and climate. As for bays, it might be a good idea to identify the geographical location and characteristics of several of them. If you've covered other bodies of water, such as streams, creeks, and rivers, it would be good to connect them to a bay. How are bays used, and how do they touch our every day lives? What about the plant life in bays? What kinds of ...
This solution provides some ideas on creating a 1st grade lesson plan about estuaries and bays, including what to include in the lesson and what the learning outcomes should be.