I'm not writing a whole essay for you but i can get it started,
Education has been the foundation of the modern age world because of the need to educate the youth of the world. Countries that live in poverty have no affordable education system or an education system at all. By making education free for everyone then society can move together as one instead of competing country against country to see which one is able to advance faster.
Three major reasons make free education for children worldwide a government's obligation. The first one is that education is the main tool and way for progress. Thus if a country wants to ensure its future it has o ensure that majority of children have access to education. The main way it can do that is by providing free education for them.
The second argument is that people with basic knowledge have proven that they have more tools and competences to face the problems of their lives. Therefore, I a government wants o to avoid supporting them as much as it can it has to ensure that it allows them to become independent adults capable of solving their day to day problems, or they will become dependant on the government.
The third factor is that education also provides critic and progressive ways of thinking to individuals. Therefore if a country looks to become better in every way in time. It has to provide its citizens with the tools to achieve it. The country will benefit from it indirectly. But it will be its best option. As countries like South Korea, Singapore, and japan provided resources to their citizens to improve and they improved their countries.
