“Find the mean number of siblings.”
Student 1: (0+1+2+3+4+5)/6 = 2.5
Student 2: (1+4+6+4+2+1)/18=1
Student 3: (1+4+6+4+2+1)/6=3
Student 4: (0+1+2+3+4+5)/18 = 0.83
What sort of misconceptions can you dig out of these student responses? If this were your class, how would you respond?