God told Aaron that he, his sons, and family are responsible for any offense against the sanctuary and priesthood.  Other Levites can assist them in carrying out their duties, but are not to come near the sanctuary or altar because they will all die. God put Aaron in charge of all the offerings to God and whatever is left from the offerings of Israel (usually 90% because they give a tenth as tithe to God through Aaron) belongs to the Levites as their inheritance in exchange for their services to God since they are not allowed to own land or property like the other 12 tribes of Israel (Joseph is split into Manasseh and Ephraim). God set Levi aside from the rest of Israel to serve God and their income is the tithe from all Israel.  So tithe was tax to the government (Levites - family of the priests). At this time, Israel had no kings, so God ruled them through the priests.                      

Numbers 19:

God tells Moses and Aaron the rules for the offering and water of cleansing. 

Numbers 20:

In the Zin desert, Miriam dies and was buried.  The people them rebelled against Moses and Aaron because they had no water and wished they had died in the desert when God struck them with a plague.  They wished they had stayed in Egypt as slaves were they had things to eat and drink.  God told Moses and Aaron to take his staff and speak to the rock in front of the people and water will come out of the rock for them to drink.  So God can bring solutions to our problems from any avenue.  Moses took is staff and struck the rock twice and water flowed out for the people and their livestock to drink.  This made God angry with Moses because God wanted him to speak to the rock to bring water, but Moses struck the rock twice.  Instead of Moses obeying God he followed the tradition of physically using the staff.  God then said that Moses will not bring the Jews to the promised land.  Moses knew how to intercede for other to God, but not for himself, he should have begged God like he always did for others (arrogance???).  Moses tried to pass thought the land of Edom (Esau their brother) with a verbal request as siblings, but Edom refused. God took Aaron away because of their disobedience about the rock and Moses made Aaron's son, Eleazar, became chief priest and the people mourned Aaron for 30 days. 

Numbers 21:

King Arad of Canaan heard that the Jews were approaching, he invaded them and captured some of them.  The Jews begged God for assistance and they destroyed all the Canaanite towns. The Jews challenged God and Moses again to demand better food and express their views that slavery in Egypt was better than their journey for freedom.  So God sent poisonous snakes among the people and many died.  It was after they repented that God told Moses to make a bronze snake on a pole so that those who look at it could survive the snake poison.  God helped the Jews to defeat the Moabites and Amorites.

Numbers 22:

When Balak, king of Moab saw what the Jews did to the Amorites, he decided to get Balaam (God's non-Jewish prophet) to place a curse on the Jews so that he could defeat them and drive them away.  Balaam inquired from God (other people knew God aside of the Jews) and God told him not to place a curse on the Jews for they are blessed, so Balamm refused to go to Balak.  Balak then sent more princes with more divination money to place a curse on the Jews, Balaam told them that the palace with all the gold and silver will not make him disobey God. Balaam asked God a second time and God told him to go with them, but do only as instructed by God.  God was angry with Balaam for asking God a second time what God had settled already because of money.  On his way, the donkey saw the angel of God with a sword and refused to move on.  Then God made the donkey ask Balaam why he beat her 3 times.  Balaam soon saw the angel and agreed to go and say only what God tells him to say.  He met with Balak and the people.        

Support Children Knowing Mathematics At A Young Age