In this lesson, students make use of repeated reasoning to discover the exponent rule  . Students begin by computing the volume of a very large cube. Next, they expand expressions written as a value with an exponent raised to another power and notice patterns when asked to write the expression using a single power of 10 (MP8). Students will extend this exponent rule to cases where the exponents are zero or negative in following lessons, but the focus here is on cases with positive exponents.