Here is a great resource and my favorite subject--Chocolate
Go to the Field Museum of Chicago and visit their interactive site, here's a class you will enjoy with your kids.
Lesson plans and worksheets are also available to download.
Cocoa Connections: From Beans to Bars - A Resource Kit for Educators contains 12 lessons—six lessons on chocolate and the environment and six lessons on chocolate and culture—that will increase your students’ understanding of the connections between humans and their environment. Each lesson outlines learning objectives, a list of materials needed, and instructional activities. The full curriculum also includes extension activities, an overview of the Chocolate exhibition, a suggested reading and film list, and classroom-friendly recipes.