When I was the 4-H Extension Agent in Prince Edward County, I worked with 6th and 7th grade teachers at PECMS to implement the 4-H Science Fair program. All 6th and 7th graders were required to complete a science fair project and make a presentation to a team of judges. Overall high scorers in each class were invited to participate in the Central District 4-H Science Fair held in Appomattox each spring.
In addition to the resources listed below, I have developed lots of materials to teach scientific investigation. (It's one of my favorite projects!) While most of these resources were created for a middle school audience, they are easily adaptable for upper elementary grades and even high school. If you have a specific need or would like to take a look at additional materials, please don't hesitate to contact me. jebowen1@vt.edu
PROJECT - Scientific Investigation Tic-Tac-Toe - Ruth Wallace and Jennifer Bowen
Scientific Investigation Review Lesson Plan
Helpful Hints for Science Fair
Scientific Investigation Word Search - Ruth Wallace, Buckingham 4-H
Mealworm Preference (project example/fun classroom experiment)
Science Fair Project Book - Ruth Wallace and Jennifer Bowen
Virginia 4-H Science Fair Contest Guide
Virginia 4-H Science Fair Score Sheet
Additional Resources from South Carolina 4-H. These are good to illustrate scientific method and would make good classroom experiments.