Justice implies adherence to the rule law rather than the rule of man. Adherence to the rule of law denies the subjective social values which those who advocate the social justice rely upon.
Social justice is an attempt to equalize outcomes, an attempt to redistribute wealth to the satisfaction of the author. As such it is essentially the rule of man rather than the rule law. The two concepts should never be attached to one another.
Your child should be told that the most efficient way to attain wealth for the most people is through capitalism. Your child should be told that the most democratic way to distribute goods and services is through the free market in which every consumer has 100% control of his vote every time he chooses to buy or not buy. A system of "social justice" is the least democratic means of distributing goods and services because it is not done by free agents operating in a free-market but by imposition of rules made not even by elected representatives but by unelected bureaucrats who are not responsible to the people they control.
Social justice is a social evil.
