I believe the answer is: the government's protection of their lives, liberty, and property.
For example, due to the existence of government, individuals have to sacrifice our ability to establish businesses however we like. But, in return the government would provide law enforcement if there is other citizens who had bad intentions toward us.
Answer:
You can do that by sending information to the parents about all the classroom rules and regulations the dos and dont's and also an explanation as to why the child has to follow these rules maybe through a mail or a letter to the parent
In the Mexican-American war, the Mexican's were not prepared for the battle: they did not have a strong enough army to handle America and they were already falling apart.
Source was History.com if you need more