To help you with world geography, try Country Reports. The children get to pick a new country every week and then research different facts about the country. At the end of the week allow them to put together a poster or give a presentation on their country. Now, you cannot keep a poster for every country done by every child. Perhaps you can keep just a one-page summary from each child and then keep them in a binder. It is really fun to get a child excited about a country when they hear it mentioned through the radio or on TV.
Here are some ideas that you can use to help them get started on the research:
What foods do the people of this country eat?
What kind of clothing do they wear?
What do the people in this country do for fun? What are their past times?
What does their national flag look like?
Do they have a national flag? What does it look like?
What does their political structure look like? Is it similar to the United States?
What are the important, basic historical facts of the country?