Factors constrained the pathway to sustainable education

Did you know that in China's Daliang Mountains, 50 children are crammed into a classroom, sharing worn books? Some children hide from the windowsill and listen to the sound of reading in the classroom. In a city tens of thousands of miles away, some children are out of the classroom on a field trip to study environmental issues. Why is it that in some corners of the world, children are still unable to enter their classrooms? Why is the promise of sustainable education only on paper in some regions? In fact, globally, more than 263 million children are denied access to basic education every year.

Problem: On our path towards sustainable development, what factors limit us from achieving the goal of sustainable education?