In this lesson, students get familiar with rational and irrational numbers by considering some of the properties of rational numbers and approximating a decimal value for some irrational numbers. In the associated Algebra 1 lesson, students examine irrational solutions to quadratic equations. Students are supported in that work by familiarizing themselves with rational and irrational numbers. Students have the opportunity to look for regularity in repeated reasoning (MP8) when they are asked about properties of rational numbers.