Swahili, English and the bilingual brain: why building a literacy platform in two languages is harder than it looks

Post 12 of 17 · The Somastars Phygital Thesis · Africa & Kenya

Grace is in Grade 4 at a public school in Eldoret. Her Kiswahili is fluent. She can tell you the plot of any Moran Hadithi Changamka story she has read — in detail. But in English, she reads slowly, loses the thread of longer sentences, and scores consistently below her Swahili performance on comprehension tasks. Her teacher says her English needs work. The teacher is right, but for the wrong reason.

Grace is not failing English because she lacks intelligence or effort. She is navigating a linguistic feature that most Kenyan literacy programmes have not accounted for: Kiswahili is a null-subject language. English is not. At the level of syntax processing — how the brain parses sentence structure — Swahili and English make different demands. A child fluent in one is not automatically fluent in the other, and a literacy platform that treats bilingual development as straightforward translation is not bilingual. It is lazy.

What the null-subject difference means in practice

In Kiswahili, the subject of a sentence is encoded in the verb itself through prefixes and agreement markers. 'Anakimbia' means 'he/she runs' — the subject does not need to be stated separately. In English, the subject must be explicit: 'He runs.' A Swahili-dominant child processing English text must actively supply subject information that their Swahili grammar has trained them not to expect. This creates a processing cost that shows up as slower reading speed and higher error rates in comprehension, particularly in complex sentences.

This is not an obscure linguistic detail. It has direct implications for how reading level assessments are conducted in Kenya and how levelled reading materials should be designed for children whose home language is Swahili.

The Kiswahili graded reader landscape

SomaStars maps its Kiswahili content to a parallel track within the 15-level taxonomy. Longhorn Publishers' Mwanga wa Kiswahili series — the CBC-aligned Swahili reader used in most Kenyan primary schools — maps to SomaStars Levels 3 through 11, from Grade 1 through Grade 6. Moran Publishers' Hadithi Changamka series provides a finer-grained progression with its own internal Level 1A through 3B structure. OUP East Africa's Swahili Readers and New Progressive Primary English series complete the landscape.

The critical design decision is that a child's Swahili reading level and their English reading level are tracked separately in the SomaStars diagnostic engine. A child performing at Level 9 in Swahili may be at Level 6 in English. The Trivia Pack for their English books is calibrated to Level 6. The Trivia Pack for their Swahili books is calibrated to Level 9. The same child. Different ZPD profiles. Different questions.

"A literacy platform that treats bilingual development as translation is not bilingual. It is lazy."

Why this matters for CBC

The CBC curriculum mandates bilingual literacy development from Grade 1. Most schools interpret this as teaching the same content in two languages — which is not the same as developing two independent reading competencies at developmentally appropriate levels. The distinction is not pedantic: it determines whether a child at Grade 4 who is strong in Swahili and weak in English is given harder Swahili books (which wastes the opportunity), easier English books (which stunts growth), or appropriately challenging content in both languages simultaneously. Only the third option builds a truly bilingual reader.

The takeaway

Grace is not struggling. Grace is doing something cognitively demanding that her literacy programme has not acknowledged: she is building two reading brains in parallel. The job of a good platform is to support both of them at the right level, simultaneously, with the same rigour.