Discuss the theme of colonialism.

Colonialism and its enduring legacy is a central theme in Second-Class Citizen. The protagonist, Adah, is an indigenous African born in Nigeria during World War II and spends her entire childhood under British colonial rule. The limited opportunities for native peoples under colonialism included limited education. The schools designated for native children were inferior to those in which the colonists enrolled their children, but some private schools were available.
Adah uses a variety of tactics to pursue her education at the Methodist school. For adults, economic opportunities in the colony were also extremely limited, which contributed to a “brain drain.” After Nigeria became independent in 1960, although people were free, conditions actually worsened in some ways when many British enterprises were suddenly pulled out. These problems contributed to the decision of her husband, Francis, to emigrate. Once she joined him in England, many of their negative experiences seem to stem from white English people's bias against the former colonial subjects.

In "Second-Class Citizen," the characters uproot their lives from Nigeria to eventually move to the United Kingdom. In the novel, their lives in Nigeria are ruled by the British overlord, as they are a colonial nation. This idea is pervasive in the novel, as the colonial mindset automatically brands the characters as "second-class citizens."
Being distant subjects of the British government, the citizens of Nigeria are not given access to high-quality education or opportunities, in spite of the effort they put forth. When Adah and Francis move to the United Kingdom, in spite of the fact that they are working hard trying to earn a decent living and supporting themselves as well as they can, they are still treated with less respect and dignity, and they don't receive the opportunities they should, simply because they are not native Brits. This theme runs throughout the novel, as they are constantly scraping to get by and make their lives better, but are very unsuccessful.