Kremikovtsi - 17 September 2018

1. Students entering classroom

2. Various second-graders sitting at desks

3. Various of first day of school welcoming ceremony at the Vassil Levski 156th Primary school

4. School Principal addressing the children and parents gathered on the first day of school

5. SOUNDBITE (Bulgarian) Valentina Kurinova, principal of the Vassil Levski 156th Primary school:

"The society should stop seeing teachers as enemies - theirs and their children's. Parents blame us for everything that happens to their children without taking into account that the work is mutual. I believe that society and parents should start supporting teachers and look at us as those who hold their children's future in their hands and should offer their utmost respect because it will be too late when we realise there is no one left to teach our children."

6. Principal looking at a notebook

7. Various of pieces of art made by the schoolchildren

8. SOUNDBITE (Bulgarian) Mariya Aleksieva, primary school teacher:

"We use the Envision software where you have one computer and many mice. They can answer questions - each one with their own mouse and the answers are kept in the system. Then we can export a statistic on how the children did on a particular question and in the whole lesson. It helps us to understand whether we taught them well, because if the whole class didn't understand it - we ourselves might be to blame."

9. Various of children sitting in Aleksieva's classroom

10. Close of Aleksieva and Yoncheva talking and looking at a book

11. Wide of Aleksieva and Yoncheva applauding the ceremony

12. SOUNDBITE (Bulgarian) Ekaterina Yoncheva, teacher in Bulgarian language and Literature

"Once you see in the eyes of a child the happiness that you have helped her somehow become a better person, nothing can turn you away from this profession any more. Even if at some point you are starting to work on something else, once you've been a teacher, you remain forever a teacher - till the end of your life. It really is a calling."

13. Close of children walking in classroom

14. Wide of the school flag during ceremony

15. School children at the ceremony

The new school year in Bulgaria has started amid a growing shortage of teachers.

On the first day of school, more than 400 positions remain unfilled across the country.

The average age of a school teacher in Bulgaria is 50 and the teachers' syndicate is predicting a shortage of almost 40,000 teachers by 2026.

On Monday morning, the Vassil Levski Primary school in Kremikovtsi, a north eastern suburb of the capital Sofia, welcomed its 170 students and 20 teachers.

This summer the principal Valentina Kurinova has had to fill three openings and is proud of having a much younger group of teachers than the national average.

She says attracting young people to the profession is difficult on the one hand because of the low wages - currently a teacher in Bulgaria is paid 380 euros (444 US dollars) a month.

Kurinova says the society sees teachers "as enemies" and that "it will be too late when we realise there is no one left to teach our children."

While more than 4,000 teachers retire every year, less than a thousand university graduates chose a career in education.

Only 8 percent of all teachers in Bulgaria are under the age of 35.

An aging demographic also means that 900 schools in less populated areas have had to be closed over the last 15 years.

Mariya Aleksieva was a student in the Kremikovtsi Primary School herself and returned to teach here 3 years ago.

She says young teachers are very important to any modern school as they bring in new methods and technology. Aleksieva uses electronic school books and diaries as well as interactive programmes in her lessons.

According to Ekaterina Yoncheva - another teacher here - the profession is very challenging and this isn't understood within the Bulgarian society.

Every year schools struggle to fill their classrooms. This often happens by having primary teachers take on extra classes with the older kids and by keeping people on who are already in retirement age.

Despite the difficulties Yoncheva says teaching "really is a calling".

"Once you see the happiness in the eyes of a child whom you have helped become a better person, nothing can turn you away from this profession anymore."

The Ministry of Education has promised to raise teachers wages as soon as next year.

They are also working on introducing new qualifications and programmes to attract young people to teaching in the hope of preventing an education crisis in less than 10 years time.