People like to rationalize or justify their cheating by convincing themselves that what they are doing is right.......”I'm underpaid; taxes are too high; Everybody cheats on their taxes; The store cheats me with their high prices; They won't miss it”. Embezzling becomes: “I'm not stealing; I'm just borrowing”. All the rationalizing in the world won't make what is wrong right. It's still wrong.
Thus it is crucial that the teacher does not tolerate any cheating among the students s/he teaches. Impress them with their sense of fairness. Is it fair that the dishonest student makes a higher grade than the honest student. The grade is a lie, a fraud. Is it fair that the dishonest student receives the award, scholarship, admission to the University, or job and the honest student does not?