Melissa, 15, had dropped out of school before she could sit the primary leaving exam in 2001. Her parents had died of Aids and she joined her grandmother in selling vegetables and fruits for a living.
But last year the new government declared primary education free, and two million new pupils entered school at the same time. Among them were 48,000 drop-outs and repeaters who joined the last year of primary school.
But the lack of places in state secondaries meant Melissa, who scored 347 out of 500 in the primary leaving exam, did not qualify.
"My aim was to join Moi girls secondary school in Nairobi and after that train as a nurse," says Melissa.
But the cut-off point for Moi girls was pegged at 390 marks.
Fifty-four per cent of primary leavers suffered a similar fate. Davies Otieno scored the best marks at Mbita primary school in Nyanza province but cannot get into any secondary. Instead, he will try to get training as a mason.
Following the abolition of fees, state schools were hit hard by overcrowding, as more than 100 pupils swamped classes meant only for 40.
"Teachers' morale in public primary schools has also plummeted as a result of poor learning facilities," says Francis Ng'ang'a, general secretary of the Kenya national union of teachers.
When results for primary exit exams were made public, private schools provided most of the 270,000 pupils now being selected to join form 1 in the 3,000 secondaries in the country. But more than 300,000 primary pupils will not get a place.
In some parts this has led to angry demonstrations by parents, who stormed primary schools with poor results. The head of Nyakaiya primary in western Kenya had to run for his life when a mob of parents entered the school compound, singing war dirges and demanding to know why their children had failed.
Without more international support, pressure groups say, children like Melissa will be condemned to a life of hawking.