Final answer:
The independent variable in Lorna's investigation is the size of the cookie dough.
Step-by-step explanation:
The independent variable in Lorna's investigation is the size of the cookie dough.
Lorna wants to know if the size of the cookie influences how long it takes to bake. In her experiment, she places different amounts of cookie dough on baking sheets and times how long it takes for the cookies to bake.
By varying the size of the cookie dough, Lorna is manipulating the independent variable to see how it affects the dependent variable (the time it takes for the cookies to bake).