LOURI, Chad — One morning, a little girl named Achta sat in the front row of this village's only school and struggled mightily with the assignment her teacher had given her.
She grasped a piece of chalk in her tiny fingers. Her face tense with concentration, she tried to direct the chalk clockwise across her slate.
She had been asked to draw a circle. What she drew looked more like a lopsided triangle.
After half a dozen tries, her teacher took away her slate and tried to hide his frustration as he wiped it clean with the palm of his hand. He held her miniature hand in his and traced a circle, then a second, then a third.
"Like this," he said. "Like an egg. See?"
Drawing a circle is considered a developmental marker. It tests fine motor skills, the use of the small muscles that control the fingers, enabling us to eat spaghetti with a fork or cut a piece of cardboard with scissors.
Children who are developing at a normal rate can trace a circle by age 3, and Achta doesn't look much older.
She is so small that you can hoist her easily onto one hip, as her mother sometimes does when she carries her to school. She is so small that when she sits on her bunk in class, her feet dangle a foot off the ground.
But Achta isn't 3. School records show she is 7 years old.
In this village, where malnutrition has become chronic, children simply have stopped growing. In the county that includes Louri, 51.9 percent of children are stunted, one of the highest rates in the world, according to a survey published by UNICEF. That's more than half the children in the village.
The struggle on display every day in Louri's one-room schoolhouse reveals not only the staggering price these children are paying but also the price stunting has exacted from Africa.
Up to 2 in 5 children across the continent are stunted, researchers estimate, which means they fall short physically and, even more devastating, mentally.
It's a slowdown that creeps across a community, cutting down the human capital, leaving behind a generation of people unable to attain their potential.
"We have a habit of focusing on mortality because the photographs are more shocking. But there is a silent phenomenon that is going on – it's stunting," says Jacques Terrenoire, the Chad country director of the French aid group Action Against Hunger. "It poses a fundamental problem for the future of a country."
Too little to learn
Elementary School No. 1 in Louri is a reflection of the village's modest means. It's made entirely of dried grass woven into a lattice held together by branches, creating a kind of grass igloo.
To enter the school, you bend down, tuck in your head and slip through a hole.
The school is organized into two rows of bunks. The smallest children sit in the front.
Last year, 78 boys and girls enrolled in the equivalent of first grade in Chad's school system. Of those children, 42 failed the test to graduate into the next grade, a percentage that almost exactly mirrors the number of children stunted in the county.
School Director Hassane Wardougou sums up the reason for the class's overwhelming failure: "They're too little," he says. "When they are this small, they don't understand anything."
Among those held back this year were 7-year-old Achta and the three boys who share her bunk – Youssouf, Mahamat and Nasruddin. Taken together, they are a window into this hidden scourge that is undermining efforts to right Africa.
Stunting is the result of having either too few calories or too little variety in the types of calories consumed, or both.
Achta's birth seven years ago coincided with the first major drought to hit the Sahel this decade.
Climate change has meant that the normally once-a-decade droughts are coming every few years. The rains that failed to fall over Chad when Achta was born failed again when she was 3, when she was 5 and when she started first grade last year.
The droughts decimated her family's herd. With each dead animal, they ate less.
Most days, Achta leaves home without eating anything. Usually there isn't anything for lunch, either. Dinner is millet flour mixed with water, eaten plain.
Her mother's kitchen doesn't have so much as a pinch of salt or a cube of sugar.
"They come to school having had nothing more than a glass of water. They can't make it till the end of the day," says their teacher, Djobelsou Guidigui. "Some fall asleep in class. Others vomit."
When a child doesn't receive enough calories, the body prioritizes the needs of vital organs over growth. What this does to the brain is dramatic.
A 2007 medical study in Spain compared the CT scan of a normal 3-year-old child and that of a severely malnourished one.
The circumference of the healthy brain is almost twice as large. Presented side by side, it's like looking at a cantaloupe sitting next to a softball.
A profound toll
This delay in the maturation of the nervous system imposes a stunning price on society.
The World Bank estimates that individuals stunted as children lose more than 10 percent of lifetime earnings. The countries in which they live lose between 2 percent and 3 percent of gross domestic product per year because of low labor productivity.
The lasting damage this causes inches across a community, leaving behind a population that struggles with the most basic of tasks.
Mr. Guidigui, the teacher, dismisses the class for recess on a recent morning. Then he sits on Achta's bunk and puts his head in his hands.
The new school year started two months ago, and half his class is repeating the lessons he first taught them in 2011. Instead of the lessons going more smoothly, the children struggle with the same simple tasks they did a year ago.
"They've forgotten everything," he says, dejected. "Really, it's not easy. You need to be courageous to do what I do."
When recess is over, Achta runs back in. She piles into her bunk. Youssouf climbs over her. Nasruddin and Mahamat wiggle into place in the bunk they are sharing for the second year.
It's time for the math lesson. Mr. Guidigui wants each child to get up and count to 10 out loud.
The teacher goes bunk by bunk, pupil by pupil.
When it's his turn, Achta's older brother counts as far as eight before getting tripped up. He is about 9 years old, and he sits in the back of the class with the older children. The performance becomes more and more muddled as the instructor works his way to the front, where the youngest children sit.
Once he gets to Achta's bunk, Youssouf stands up, looks at his feet and mumbles his way up to five. Achta is last, and by the time the teacher calls on her, she's heard 40 other children repeat the sequence. She stands and smiles shyly at her instructor.
Even the number 1 escapes her.
A worsening situation
A gust of wind sweeps into the schoolhouse. It comes in through the spaces between the dried grass, blowing a horizontal shaft across the bunks. For a second it fills the awkward silence as a 7-year-old girl struggles to perform a skill normally attained by the age of 4.
Progress on reducing stunting has been painfully slow, in part because the phenomenon does not rise to the level of an emergency.
Globally, the percentage of stunted children fell from 39.7 percent in 1990 to 26.7 percent in 2010, according to a report by Save the Children.
It's Africa, though, that is paying the highest cost.
The continent has seen an overall reduction in stunting of just 2 percent in 20 years, and today more than 38 percent of children in Africa are stunted, the report says.
In fact, slow progress combined with population growth means that by 2025, 11.7 million more children will be stunted in Africa than today, the London-based charity found.
Two decades ago, Asia and Africa had nearly the same rate of stunting, but Africa has stagnated while Asia has leapt forward.
Analysts say there is a direct link to progress in agriculture. In Africa, the yields of staple cereals are one-third of those in Asia.
The parents of Achta and her bunkmates live off the land exactly as their forebears did. What's changed is the sky above them.
The village of Louri is located on a ledge of sand a seven-hour drive from the nearest paved road. The sun is so bright, it bleaches the landscape white. Almost nothing takes root here.
For generations, the people of this bone-dry region lived off their herds. They drank the herds' milk for protein and sold what was left to buy the many things that cannot be produced in this village, starting with vegetables.
When the rains were plentiful, the wild grasses around the village stayed green for months at a time.
Now they are only green for a brief flash, right after the short-lived rains.
For the rest of the year, the fields are the dull color of cream of wheat. The village's animals are in sync with the land, giving birth and producing milk only when the grass is at its most nutritious.
Without milk, the villagers are forced to sell their animals, usually a calf or a foal, for cash to buy basic staples.
The families of Achta, Nasruddin and Mahamat had no baby animals to sell in recent months, so their kitchens are bare. The flour they eat day after day lacks folic acid, iron, zinc and vitamin A, micronutrients that are crucial to a child's development.
Only Youssouf's family had a goat that recently gave birth. The parents sold the kid at the market for $15. Youssouf's mother used some of the money to buy dried okra and sun-dried tomatoes.
There is no electricity in the village. That means there are no refrigerators. So even when people are able to buy vegetables, the only ones that make it to this remote backwater are preserved.
Youssouf's mother keeps the dried vegetables on a pot lid, stored behind a curtain. Each week, the little boy is allowed a few tiny pieces, like a treat.
Malnutrition and disease are intertwined, with lack of food leading to a weakened immune system and illness.