Achebe's biography can help explain some of the cultural and historical conflicts he may be addressing through the story.
On a universal level, a couple of themes can be seen. One important idea in the short story is cultural respect and awareness. The teacher does not show the community members' religious and spiritual beliefs the proper respect. He takes away the path that means so much to their spiritual lives, so they retaliate by taking away what he treasured most--the superficial improvements he made to the school. In fact, his gung-ho efforts to improve and educate is deemed "misguided zeal."
While the story reads moreover like an objective account, it appears the teacher has good intentions in his attempt to improve the school grounds and rid the community of what he sees as "superstitious" ways. Nonetheless, his good intentions lead to disaster. That is the irony of good intentions sometimes: the best plans can breed the worst results. Oftentimes we seek to change others and the world around us based on our own ideas of improvement and advancement, but we can not expect everyone's definitions of improvement and advancement to match our own.
Very often, people underestimate the gap between two cultures, assuming assimilation and integration is much easier than it ever could be in actuality. The gap between some cultures can be more accurately defined as a chasm. We cannot always build a bridge to the other side. Sometimes we have to be content to smile and wave from the other side.