Chubby, clumsy and unfit - it would be an understatement to say that I was not good at sport at school. I puffed and stumbled my way through our physical education classes and always hoped dearly for rain when it came to our annual sports day.

But while other girls feigned illness or skipped school when it came to the time of the week when we had to change into our sports clothes, I dutifully trundled out into the playground and jogged around behind the others. It was my teacher who made all the difference. She encouraged me, pushing me to run those extra meters and rewarding me for my efforts, keeping me going.

It’s teachers like these that we remember – those that were particularly good…or maybe particularly bad. Those that really make a difference to the way we continue to live our lives. No, I didn’t go on to do professional sports, but my teacher did show me that I could keep going, even when I want to give up.

I was lucky enough to have not just one teacher like this, but a few throughout my school years. But these are lessons that not all children get the chance to learn. Many never even have the opportunity to go to school in the first place - around 58 million, according to a recent report released by the United Nation's Educational, Scientific and Cultural Organization (UNESCO).

For those pupils, the problem is obvious - and efforts are being made to make sure that all children are provided with access to education. Many governments have abolished fees, are working to build new schools and have employed either full-time or contract teachers to fill the gaps.

But even for those students that do make it to school, it doesn't necessarily mean they will be getting a quality education.

(Un)Trained teachers

"Good education has to provide students with competencies they need for further education and for being successful in everyday life and in their vocational practice on the job," says Eckhard Klieme, director of the Department of Educational Quality and Evaluation at the German Institute for International Educational Research (DIPF).

Ensuring a "good education" means having not only having enough teachers, but enough trained teachers to support the number of pupils, and access to resources such as schools and textbooks. But it's not as easy as it sounds and there are many countries that have been struggling to provide for their children.

The world's governments have made some clear headway in reaching some of the UN's Education for All goals. These call for targets including access to free education for all children and a 50 percent improvement in adult literacy.

One third of the 164 countries involved have achieved all the education goals and half of the countries have all their children attending primary school. But there is still a long way to go: More than four million trained teachers are still needed worldwide.

It's a big problem particularly in Sub-Saharan Africa, where high numbers of children to teachers has seen authorities try to solve the issue by hiring untrained teachers. That has led to children-teacher ratios in primary schools of 42:1 on average in Sub-Saharan African countries. But if you take out the number of untrained teachers, the ratio skyrockets to more than 100 school kids per one teacher for countries like Central African Republic, Chad Guinea-Bissau and South Sudan.

What is better: an untrained teacher or none at all?

To be considered trained, those going into teaching profession should be competent in their chosen subject, at least to secondary education of "appropriate quality and relevance." But as well as academic ability, they should also have sound pedagogical strategies in place - how to deal with their class, teaching children of different abilities and ages, skills that come with formal training.

While hiring teachers without these qualifications might get more children into schools, it can also "jeopardise education quality", according to the report. Asked whether it was better to have untrained teachers rather than no teachers at all, Nihan Blanchy-Koseleci, who specializes in education quality and teachers at UNESCO, said: "Children definitely need to be in school, but what there needs to be is a policy of making sure there are enough teachers and that enough are trained."

Klieme agrees, but adds that deep academic knowledge of a particular subject is not enough.

"Teachers who have academic training are better prepared to provide quality education to students. [But] teachers should know how to teach their subject," he says. "This is different from subject matter knowledge - you can be an excellent biologist without knowing how to teach biology."

Still, countries all over the world are lacking the incentives to attract people into what amounts to years of training to learn how to properly teach.

The incentives to teach - in developing and developed countries

Life Links reporter Carolina met young teacher Aleks in the episode #AforEffort. Where Aleks lives in Bulgaria, wages are so low for educators - around 250 euros per month - that there are a shortage of those willing to train. And many of those that do, struggle.

"Someone selling shoes would get more money - approximately 400 euros," says Emil Jassim, an expert on education in Bulgaria, adding that it also means that only three percent of teachers in Bulgaria are under the age of 30. "Seventy-five percent of the teachers should be pensioned and should retire in about six years."

And it's not just a problem in the developing world.

"In Western countries it's getting more difficult to recruit people for the teaching profession because being a teacher is quite a hard job and there are other jobs that are better paid," says Klieme.

But it's not just a question of income, that holds people back from wanting to become teachers. The status of teachers in the US and much of West Europe is also putting potential trainees off, say experts.

In some countries, teaching is seen as a "second-best option" after graduating. But social perception of teachers vary across the world. According to the 2013 Global Teacher Status Index, teachers in China, Greece, Turkey and New Zealand are afforded the highest respect - in China they are seen as having a similar social standing as doctors. However, in countries such as Israel, Brazil, Czech Republic and Italy, they are not well respected.

NGOs battling for quality education

To combat the shortage in the number of teachers, some western countries have also attempted to fill the gap with teachers lacking formal training. In the UK, for example, the government has allowed state-funded academies to hire unqualified teachers. But the move has been highly controversial.

There are organizations trying to battle the trend, working to ensure teachers are qualified. The NGO training #AforEffort's Aleks, Teach for Bulgaria is one such program. Part of the Teach for All network, Teach for Bulgaria works in "encouraging and preparing capable and ambitious young people to become inspiring teachers and leaders in our educational system and society", according to its website. Such programs are in place all over the world and seem successful: School kids get similar results in reading and maths and some of the initiatives have been credited for improving standards at schools.

Meanwhile, governments such as in Guinea have been working to have been trying to combat the problem of contract teachers - temporary educators, less likely to have training than fully employed teachers - by implementing a policy where they receive at least 18 months of training.

Still, the measures are too few.

New goals as part of UNESCO's Education for All initiative are due to be set, but the organization predicts that another $22 billion in funding is still needed to ensure basic education.

But it won't just take money - it will also take time. And until then many children will remain in limbo, without even a basic level of schooling.