We travel to Mexico to find out why so many Mexican children drop out of school to join the country's workforce.

"Education for everyone" has been a popular slogan since the Mexican revolution more than 100 years ago.

But according to the Organisation for Economic Co-operation and Development, eight out of 100 Mexican children who enroll in elementary school do not show up for classes.

Twenty percent of our public spending is spent on education. But every year, we see that billions of dollars are diverted from education ... So schools aren't getting in the first place what they need. We have a system where about one out of every four public schools doesn't have a bathroom ... where kids don't have chairs. Jennifer O' Donoghue, Mexicanos Primero

While barely 50 complete middle school, 20 graduate from high school, 13 get a bachelor's degree, and only two become graduate students.

A study released by UNESCO last year says the children who don't attend school are mostly working. The report reveals that at least 21 percent of all Mexican youth between the ages of seven and 14 drop out of school - that's around 651,000 children.

That means Mexico has one of the largest child labour forces in Latin America, second only to Colombia.

Many of Mexico's youths who don't attend school work in plantations.

Talk to Al Jazeera travelled to the coastal state of Veracruz to meet some Mexicans who have traded classrooms and pencils for sugar cane fields and machetes.

Sixteen-year-old Albino was just 12 when he became a plantation worker. He has spent the past four years in different areas of Mexico following the harvest of fruits and vegetables.

Albino sees his family every 20 days. He gives them half of his salary. He says he regrets leaving school, but is proud that he can help his parents with money.

"You just devote yourself to work and you're proud that you no longer play with small children," he says.

We also met 14-year-old Fernando, who dropped out of school two years ago because he was bored.

"On most days I get up at 5am and work until 6pm ...There were days when I'd have preferred to have been at school, when I regretted quitting. After my first day at work, I didn't want to go back. I regretted having left school, but I am fine now. I like working in the fields now," Fernando says.

Fernando's father, Pablo, says he wanted to finish school himself, but he had to work to support his family. He'd always wanted Fernando to have the education he couldn't have. But when Pablo realised his son wasn't committed to his studies, he wanted to ensure that Fernando at least wouldn't be lured into a gang.

He says he wanted his son to develop a work ethic and learn to support himself. So the two of them travel across Mexico - from one harvest to the next, toiling side by side.

READ MORE: Child labour and the perils of a lost education in Mexico

One of the ways Mexico has tried to keep children in school is through the so-called Prospera programme. It was launched in 1997 and offers what NGOs call "conditional cash transfers".

The payments are an incentive for parents to keep their children in school and, in exchange, the families have to meet certain requirements and attend workshops including sex education and family planning.

Single mother Reynalda Barragan Pastrana says the Prospera programme changed her three daughters' lives.

"[Before we joined the programme] we were all living in one room that was five by five metres, which was made out of tinfoil and cardboard. We didn't have a floor, it was just earth. Once we began getting support from the programme, we were able to improve our home and my daughters started going to school," she says.

However, the Mexican children who remain in school aren't doing well when compared with students from other member states of the Organisation for Economic Co-operation and Development. Overall, Mexico's students score 81 points below the OECD average in subjects such as mathematics.

Like many aspects of life in Mexico, corruption plays a role in its education system.

Jennifer O' Donoghue, who works for a civil society organisation that's dedicated to improving education in Mexico, says the misuse of money meant for schools and poorly trained teachers are two of the reasons why Mexico's public schools are failing children.

"It's the responsibility of the state to guarantee that those children are there in the school. So it's not about school drop-out, it's about school systems that exclude young people ... Individual children are lost in a system that sees them as numbers," she says.

In 2013, Mexico introduced education reform with the aim of improving the system through teacher evaluations, professional development, and more federal oversight over budgets.

Long-held practices of "ghost teachers" collecting salaries or handing teaching positions from one family member to the next were expected to disappear.

But the reform hasn't been implemented due to opposition. There have been months of violent protests and school closures over the proposed reforms - and negotiations are continuing.

Meanwhile, hundreds of thousands of Mexican children drop out of school every year to join the country's workforce.

Source: Al Jazeera