Students learn about kites and gliders and how these models can help in understanding the concept of flight. They learn about the long history of human experimentation with kites, the eventual achievement of flight with the invention of airplanes, and the pervasive impact of the airplane on the modern world (pros and cons). Then students move on to conduct the associated activity, during which teams design and build their own balsa wood glider models and experiment with different control surfaces, competing for distance and time. They apply their accumulated existing knowledge (from previous lessons and activities in this unit) about the four forces affecting flight and modifiable airplane components, and apply an engineering design methodology to develop sound gliders. To conclude, they reflect on and communicate the reasoning and results of their design modifications.