The sons of Amram: Aaron and Moses. Aaron was set apart, he and his descendants for ever, to consecrate the most holy things, to offer sacrifices before the LORD, to minister before him and to pronounce blessings in his name for ever.
These were the descendants of Levi by their families-- the heads of families as they were registered under their names and counted individually, that is, the workers twenty years old or more who served in the temple of the LORD.
The duty of the Levites was to help Aaron's descendants in the service of the temple of the LORD: to be in charge of the courtyards, the side rooms, the purification of all sacred things and the performance of other duties at the house of God.
They were in charge of the bread set out on the table, the flour for the grain offerings, the unleavened wafers, the baking and the mixing, and all measurements of quantity and size.
and whenever burnt offerings were presented to the LORD on Sabbaths and at New Moon festivals and at appointed feasts. They were to serve before the LORD regularly in the proper number and in the way prescribed for them.
And so the Levites carried out their responsibilities for the Tent of Meeting, for the Holy Place and, under their brothers the descendants of Aaron, for the service of the temple of the LORD.