New Revised Standard Version
to determine when it is unclean and when it is clean. This is the ritual for leprous diseases.

New American Bible
to give direction when there is a state of uncleanness and when a state of cleanness. This is the ritual for scaly infection.

Douay-Rheims Bible
That it may be known when a thing is clean or unclean.

That it may be known when a thing is clean or unclean.

teach

Leviticus 10:10 And that you may have knowledge to discern between holy and unholy, between unclean and clean:

Jeremiah 15:19 Therefore thus saith the Lord: If thou wilt be converted, I will convert thee, and thou shalt stand before my face; and thou wilt separate the precious from the vile, thou shalt be as my mouth: they shall be turned to thee, and thou shalt not be turned to them.

Ezekiel 44:23 And they shall teach my people the difference between holy and profane, and shew them how to discern between clean and unclean.

this is

Deuteronomy 24:8 Observe diligently that thou incur not the stroke of the leprosy, but thou shalt do whatsoever the priests of the Levitical race shall teach thee, according to what I have commanded them, and fulfil thou it carefully.