byjus.com › us › math8th Grade Math, Curriculum & Online Math Classes for Grade 8 ... Here, 8th grade math students will learn to find cube roots of numbers with which they are already familiar. Perfect cube of numbers Rational numbers. A rational number is a number that can be expressed in the p q form, where q 0. Eighth grade math students will learn the properties of a rational number in this section. Irrational numbers