I've always found that focusing on a single course of study in science or social studies may be more beneficial than the hit and run method of imparting facts and information on several different topics. Children benefit from delving deeper into a single topic over a longer period of time.
I recall my college days when I was taught how to plan units of study. The focus is a single topic around which a series of lessons are designed that integrate the various curricular areas. In the end the teacher's work pays off because he has a nice binder with all the activities for the unit sewn together and it can be used year after year until retirement. That's not exactly how I like to operate, mostly because it would bore me year after year to do the same thing. Truth is, I don't have a file where old activities and units are stored for easy retrieval. For me, each year is a new experience, perhaps a different unit or a different approach to the same unit.
Teaching on Ecosystems
For my ecosystems theme I don't have a binder I pull out and recite from annually with the new group. I know what my goals are with this course of study and from there everything is up in the air. I decide many of my lessons as I go (with the end goals in mind), and some of what I pull together is inspired by the kids' interests. That's why it's hard to repeat the same lessons every year because the kids change every year and with different kids come different interests.
My goal with a unit on ecosystems is that children come to learn that living organisms do not live separate from other living and nonliving things, and that their existence is maintained by their dependency on other organisms and the other organisms dependence on them. This delicate interdependency is the heart of an ecosystem. I also want them to learn that natural and human interference to an ecosystem can be detrimental to the functioning of that ecosystem, and that within a given ecosystem there are distinct organisms that are part of a food chain, have special adaptations to survive, and use nonliving things as part of their survival.
With those general ideas to convey, the ocean of possibilities can swarm. Unit plans generally are devised with standards in mind, rationales....that's tiresome to think about, but rest assured when you're growing and maintaining eco-columns, journaling observations while at special field trips to environmental centers, researching organisms that are part of distinct ecosystems, building models and dioramas to illustrate a unique ecosystem, writing fictional stories about animals living together in an environment, putting on a silly play about pond life etc. you'll be meeting standards you never dreamed of.
What do we Know?
So, where to begin. A great way to start any unit plan is to find out what the children know and what they want to know on the subject. Put up two pieces of chart paper, one titled "What I know about how living things depend on each other," and the other titled "What I want to know about how living things depend on each other."
For chart one, give the children time to think about the statement and jot down all their background knowledge on the subject in their science notebooks. Proceed by allowing them one at a time to share their facts and make sure to jot down their facts and information on the first chart. When that chart is filled to capacity repeat the steps for the second chart, only this time challenge them to think about what they might want to discover during the course of the study.
At the end of the session you should have two pieces of chart paper chock full of information about where they are with their knowledge, collectively speaking, and where they want to go. Teachers will gain better insights into what lessons to plan by starting with this activity. Throughout the study and at the end of the study teachers should return to the chart to add more information to chart one and check to see if all the inquiries for chart two are being answered.