However, making a student do the following exercise is a waste of time:1*2 = ?2*1 = ?2*3 = ?3*2 = ?3*4 = ?4*3 = ?This teaches them nothing of commutativity, unless you make that student do the exercise before giving them the definition or the word commutative (or even telling them that a word exists for that function), which then lets the student find out and affirm what they probably already knew