On the Atrai River in the northwest of Bangladesh, a small beige boat is tied up in tall grass that lines the riverbank.
The interior of the boat is packed with narrow benches which in turn are jammed with children.
There are 29 students in this third-grade class and it would be hard to fit any more into the narrow vessel. The kids sit shoulder-to-shoulder facing a blackboard at the back of the boat.
When the teacher asks for a volunteer to recite a multiplication table, 8-year-old Nila Khatun's hand shoots straight toward the unpainted ceiling.
She leads the class in a chant that begins with "6 times 1 equals 6" in Bengali. They end with "6 times 9 equals 54."
Educators in Bangladesh have a problem. Not only do they face many of the same challenges as teachers in other resource-poor countries — funding constraints, outdated textbooks, overcrowded classrooms — they also have to worry about monsoon rains. Flooding is so common in Bangladesh that students often can't get to the classroom.
So one local charity has decided to take the classrooms to the students in the form of schools on boats.
This boat is one of 23 floating year-round schools in this part of Bangladesh run by Shidhulai Swanirvar Sangstha, a local nonprofit group.
Each morning the boat goes along the river picking up students. Once the whole class is on board, they pull over to the riverbank and school starts for the day.
In addition to their standard primary school classes of Bengali, English, math and science, the students also watch a video about the adventures of Meena and her pet parrot, Mithu. Meena is an educational series developed by UNICEF and is the closest thing South Asia has to Dora the Explorer. In the episode that Nila and her classmates watch, Meena and the parrot foil a plot to marry off a young girl for a dowry of a motorcycle.
Bangladesh is not only the eighth most populous nation in the world with 160 million people, it is also one of the countries most prone to flooding.
The nation sits in a vast delta formed by the Ganges, the Meghana and the Brahmaputra Rivers as they carry brown sediment-rich water from the Himalayas out to the Bay of Bengal.
Much of the country is less than 16 feet above sea level. In heavy monsoon rains, 70 percent of the country can end up under water.
Mafya Begum, the lone teacher on the boat, says that during the monsoons, the local villages are cut off from the rest of the world. The roads end up under water and the only way out is by boat.
Mohammed Rezwan, the founder of Shidhulai Swanirvar Sangstha, grew up in this part of Bangladesh.
"If you visit these areas you'll find that during the monsoon season they get isolated," he says. "It becomes very difficult to have the normal life."
Rezwan started his first floating school in 2002.
"If the children can't go to school for lack of transportation, then the schools should go to them," Rezwan says. "The idea was to ensure all-year-round education."
His nonprofit now runs 23 boat schools in this part of Bangladesh. Shidulai also operates five floating medical clinics and just launched a playground-slash-library that plies the rivers. All their services are free. Rezwan says Shidhulai pieces together funds from national and international groups as well as individual donors to pay for its programs.
In 2005, Shidhulai won an Access to Learning Award for $1 million from the Bill and Melinda Gates Foundation (which is a funder of NPR and this blog). The group won a U.N. Prize for Inspiring Environmental Action in 2012. In 2006 UNDP honored Shidhulai with its Equator Prize and said the group is "transforming the region's waterways from obstacles to human development into pathways for education, information and technology."
Groups like Shidhulai have helped Bangladesh make dramatic social progress over the last quarter century. The country has cut its poverty rate in half since the year 2000. It graduated from being a "low-income" to a "lower middle-income" country in 2015, according to the World Bank.
The economy is one of the fastest growing in the world.
But much of that economic boom hasn't been seen in the rural backwaters of Bangladesh.
Rezwan says it's important to make sure that Bangladesh's annual floods don't keep kids from these remote areas from school and trap them in poverty.
He refers to the floating classrooms as a combination "school bus and school room."
After the morning session, the boatman fires up the diesel engine on the boat-school, delivers the students back to their villages and then picks up a group of older kids for the afternoon classes.
Rezwan says the mobility of these schools has another benefit in rural Bangladesh.
"In the rural areas. the parents are mostly concerned with the safety of the girls," he says. "If they [girls] have to travel a long way to go to school, then the parents would not let them go to school. But here the education comes at their doorsteps so they're not concerned about the safety."
And that's true for the family of third-grader Nila.
Her mother Musa Khatun says that if it wasn't for the floating school, Nila probably wouldn't be in school at all.
"There's no school nearby," Khatun says. "There's a school far away. That's why they chose this boat school."
Nila lives with her parents and her baby sister in a two-room house in a fishing village on the Atrai river. The walls are little more than woven reed mats. There's no electricity in the village except from some small solar panels that some residents have on their roofs.
Khatun says that during the monsoons the village is only accessible by boat. Their family primarily survives by raising jute in the nearby plains. The long, fibrous plant is used to make burlap bags. Nila's mother, however, sees a different future for Nila. She says Nila is the smart one of the family. No one in their family has ever gone to college, yet Khatun insists her daughter is going to be a doctor.
And Nila nods her head enthusiastically.