These questions are in order of increasing depth. The first two involve basic issues of place-value decimal notation. The third involves rational numbers and also involves division, the most difficult of the arithmetic operations. It further requires
“modeling” or “representation”—connecting a calculation with a “real-world” situation. The last problem, which was originally stated in terms of perimeter and area of a “closed figure”, potentially involves very deep issues. Even if one replaces
“closed figure” with “rectangle”, as all the teachers did, one must still compare the behavior of two functions of two real variables.