The notion of "fair-test" experiments comes from the United Kingdom, where this phrase is used as more accessible alternative for students than them doing the "scientific method." Developmentally, quite young children (age 6-7) have a workable notion of fairness, which they can apply to test settings, and involves maintaining experimental conditions across tests and controlling variables so that usable data gets generated.

In MOVIE 1, Vanderbilt's Richard Lehrer distinguished between students conducting tests and controlling variables and designing investigations. He suggests that variable control is less challenging than having students suggest ways to investigate questions they pose, and reason about the tradeoffs of different investgation designers. What questions does Lehrer suggest raising with students? Did the three teachers doing the Model Parachute activity in Variables & Fair Tests have students designing investigations, or doing something else?