Irrational Numbers on the Number Line

There are four irrational numbers that participants need to graph. Pi(π), -(½ x π), and √17 are easy to approximate with common rational numbers. On the other hand, the commentary describing the irrational number 2√2 is not clear. It might be easier to list the squares of rational numbers that the class would know:  1.12 = 1.21, 1.22 = 1.44, 1.32 = 1.69, 1.52= 2.25. A close rational approximation for √2 is 1.4, therefore 2√2 ≈ 2.8.