Students use repeated reasoning to discover the exponent rule 
(MP8). Students work with expressions where n and m are positive integers and n > m. Students extend to the case where n = m to make sense of why 100 is defined to be equal to 1 and critique a faulty argument that it should be defined to be equal to 0 (MP3). Students recognize that separating the same number of factors from the numerator and denominator, then dividing has the effect of multiplying by 1.
Grade 8, Episode 18: Unit 7, Lesson 4 | Illustrative Math
