As a new school year begins today, more than 3.5 million children are already missing out on education - and that number is predicted to rise dramatically due to security fears and other problems.
Afghanistan's progress in educating its children is under threat, as growing insecurity and corruption shut more schools and reduced international funding undermines a system struggling to cope.
Rising school attendance, up from fewer than a million when the Taliban were ousted from power in 2001 to more than seven million today, has been held up as a major success in efforts to rebuild Afghanistan from decades of war.
But advances in lifting enrolment have stalled, money earmarked for new school buildings misspent and thousands of "ghost teachers" have damaged the quality of education.
More than 3.5 million children, one in three Afghan kids, will miss school at the start of the school year, which began today, and the number is predicted to rise.
Education Ministry spokesman Mujib Mehrdad said it was hard to say exactly how many more children were out of school but the situation had deteriorated after years of progress.
Last year, rising insecurity forced 1006 schools to shut, more than double the number of 2015, he said
Save the Children predicts the total number of Afghans missing school will rise by more than 400,000 this year due to insecurity and because many of the up to one million Afghan refugees expected to return from Pakistan in 2017 are children who will not make it to school.
"From the early morning until the evening I am busy collecting paper from garbage to feed my old parents who are at home," Sayed Agha, 13, told Reuters in the southern province of Kandahar.
"If I go to school, my parents will be hungry because they have no one to feed them."
Kobi primary school in Kandahar is typical of the poor conditions for many who do make it. Designed for 1500 children, only about two-thirds turn up and many attend classes under a tent.
Sharifullah Sahrif, a teacher, said many parents kept children at home, fearing kidnapping and violence.
We don't have chairs, we don't have desks, we don't have classes, we don't have electricity or sports areas.
International support - USAID has spent about $868 million on Afghan education programmes - has helped millions into school.
But progress has been uneven and Afghanistan has the third highest rate of children missing primary school after Liberia and South Sudan.
According to the Education Ministry, 9.2 million children are officially enrolled but about two million do not attend.
A government investigation in 2015 uncovered allegations of embezzlement, nonexistent ghost schools, ghost teachers and doctored statistics, the Special Inspector General for Afghanistan Reconstruction, a United States watchdog, said last year, citing local media reports.
Ali Yawar Adili at the Afghanistan Analysts Network said there was huge mismanagement, citing the case of the Education Ministry printing thousands of incorrect school textbooks that now sit rotting in a Kabul storeroom.
"The numbers of children and the quality of teaching, and the number of teachers, they cannot be trusted," he said.
Merhdad at the Education Ministry said the government was working hard to improve transparency. But conflict and decreasing international funding, on which the government depends to pay for textbooks and school buildings, made it difficult to reverse recent setbacks.
"Something has to give soon," said Ana Locsin, Save the Children's Afghanistan country director.
"Which is why we are urgently calling for greater investment in aid and education so that the progress made in Afghanistan over the past 10 to 15 years, particularly in girls' schooling, does not come undone."