Jahath was the oldest son and Ziza was the second son. But Jeush and Beriah did not have many children. So Jeush and Beriah were counted like one family.
Amram's sons were Aaron and Moses. Aaron was chosen to be very special. Aaron and his descendants were chosen to be special forever. They were chosen to prepare the holy things for the Lord's service. Aaron and his descendants were chosen to burn the incense before the Lord. They were chosen to serve the Lord as priests. They were chosen to use the Lord's name and give blessings to the people forever.
These were Levi's descendants. They were listed by their families. They were the leaders of families. Each person's name was listed. The people who were listed were 20 years old or older. They served in the Lord's Temple.
David's last instructions for the Israelites were to count the descendants from the tribe of Levi. They counted the Levite men who were 20 years old and older.
The Levites had the job of helping Aaron's descendants in the service of the Lord's Temple. They also cared for the Temple yard and the side rooms in the Temple. They had the job of making all holy things pure. It was their job to serve in God's Temple.
They were responsible for putting the special bread on the table in the Temple and for the flour, the grain offerings, and the bread made without yeast. They were also responsible for the baking pans and the mixed offerings. They did all the measuring.
The Levites prepared all the burnt offerings to the Lord on the Sabbath days, during New Moon celebrations, and on the other special meeting days. They served before the Lord every day. There were special rules for how many Levites should serve each time.
So the Levites did everything that they were supposed to do. They took care of the Holy Tent and the Holy Place. And they helped their relatives, the priests, Aaron's descendants, with the services at the Lord's Temple.