Numbers 18 - God placed a lot of responsibility on the Levites. He knew Aaron and his sons would need help and He set aside their brethren to assist them. But He made sure they understood the limits of their work and they were not to come in contact with any of the holy furnishings. The Levites would receive gifts from the people for their ministry, they would also be required to tithe their earnings to the Lord, just like every other Israelite. God wanted all His people to know the importance of giving to remind them even their God gives.
Numbers 19 - God ordered a red cow to be sacrificed and burned. The ashes would be kept for use when an Israelite became contaminated from a corpse. The ashes would be combined with water and the individual would wash themselves to remove all contamination. It was another way God wanted holiness in the lives of His people.
Numbers 20 - There's a lesson to be learned in this chapter regarding allowing complaining and murmuring to influence your judgment. Frustration is never an acceptable excuse for pride and arrogance. Moses and Aaron were to speak to the rock to bring forth water but they hit the rock instead and said, "Must we give you water..." This act cost them dearly - they were not permitted to enter the Promised Land themselves. The deaths of Miriam and Aaron are recorded in this chapter.