National Council of Teachers of Mathematics' (NCTM's) "Principles to Actions: Ensuring Mathematical Success for All" outlines eight teaching practices for effective teaching and learning of mathematics (NCTM 2014). One of the teaching practices, "elicit and use evidence of student thinking," states, "Effective teaching of mathematics uses evidence of student thinking to assess progress toward mathematical understanding and to adjust instruction continually in ways that support and extend learning" (p. 10). The problem scenario presented in this article has students respond to questions about cutting a rectangular cake into fair shares. The problem allows for students to make their thinking public so that, if necessary, teachers can adjust the task and questions to support and extend students' geometric thinking with respect to transformations.