What did your teacher tell you after you said that?
The example she gave was about people sharing a house. One guy goes out and works hard and makes a lot of money, one mows lawns as a part time job, and the third watches TV all day.
Would it be fair for them to all divide all their money equally?
Pretty obvious, even to a third grader, that this wouldn’t be just.
Pretty obvious, to an “adult” leftist, that this WOULD be a just solution.