This paper illustrates the role of a Thinking-about-Derivatives task in identifying learners' derivative conceptions and for promoting their critical thinking about derivatives of absolute value functions. The task included three parts: Define the derivative of a function f(x) at x = x0, Solve-if-Possible the derivative of f(x) = |x| at x = 2 and at x = 0, and evaluate the correctness of suggested solutions in a Right-or-Wrong part. Three prospective teachers, Noa, Anat and Daniel were individually interviewed when solving the task. We found that while the participants correctly solved the Define part, they exhibited some erroneous images in the Solve-if-Possible part, and their work on the Right-or-Wrong part contributed to their critical thinking about functions and derivatives. All three participants expressed their appreciation of their work on the Right-or-Wrong part of the task.
- Absolute value function
- Right-or-Wrong tasks