helicopter design challenge, students measure many variables in their process of designing the slowest helicopter. They may choose to explore paper type, mass of the helicopter, wing length or width, weight at the base of the helicopter, or another variable - They will accurately measure the changes in these variables. They will also measure the amount of time it takes for the helicopter to hit the ground. Students will use evidence from the data of previous trial to modify their helicopter design in order to create the slowest falling design. Scientific Knowledge is Based on Empirical Evidence