I hate to be the person who mentions 'back-to-school' when it is still only early August, but in my defence students here in the US return earlier than in Ireland and they will be back at their desks in the coming days and weeks.

The school calendar may be different here but there is one thing that the education systems in Ireland and the US have in common and that is teacher shortages.

It is a big problem across the US.

The number of college students training to become teachers is falling and there is also an increase in the number of existing teachers leaving the profession.

Among the reasons listed by those who quit are pensions and healthcare, violence in the classroom, a lack of resources and pressure to boost test scores.

Here in the US, schools are rated based on academic performance and it is easy to look-up what score your local school has achieved.

If you have children, this dictates where you choose to live. When you click on a listing on a property website, for example, you will get the usual descriptions of bedrooms, amenities and location but you will also see the rating for the local schools in the area.

One of the biggest problems facing teachers in the US is low pay, particularly when you consider how expensive it is to go to college here. Most people are saddled with massive student loans after they have finished their studies and you need a good job to pay off those debts.

A recent study from the Economic Policy Institute showed that US teachers are paid a lot less than other college graduates, with weekly wages more than 20% lower than non-teaching professions.

Many teachers are forced to take on second jobs at evenings and weekends such as coaching, giving grinds and working in shops.

The hardest teaching jobs to fill are in science, technology and maths because those graduates can earn a lot more in the corporate world.

The average teacher's salary in the US right now is around $60,000 a year but it varies widely from state to state. In New York and Massachusetts, it is almost $80,000 a year but it is half that in states such as South Dakota and Mississippi.

That has created a situation where states compete against each other to attract teachers.

Last year the case of high school teacher Rene Castillo made headlines because it was the perfect example of this issue.

Rene was working in Arizona but decided to leave that school and take a job across the state line in California.

It meant a longer commute but he doubled his salary.

There are also salary differences within individual states. 

Staying in California for example, the superintendent of schools for Santa Cruz County recently said that he struggles to retain staff because he is competing with the nearby county of Santa Clara where teachers can make up to $20,000 more a year. 

So what are the authorities doing to address these teacher shortages?

Some states have simply increased pay and are also offering cash stipends to attract graduates.

Other states have increased the number of teacher training programmes in colleges and have changed the qualifying requirements in a bid to lower the cost of entering the profession and shorten the length of time required to get a qualification.

It is hoped this will also help to improve diversity in education and attract more candidates from minority backgrounds.

In some parts of Kentucky teacher shortages have been classed as critical with literally nobody applying for advertised jobs.

As part of a recruitment drive, some Kentucky high schools are running a programme that trains students who are interested in teaching in the hopes they will choose it as a career path when they go on to college.

Many schools have had to resort to long-term substitutes, provisionally licensed teachers who are not fully qualified and retired teachers who have been asked to return to the classroom.

In Oklahoma, hundreds of emergency-certified teachers have been approved. This was originally designed to be a temporary measure but it is becoming the norm.

Some high schools have had to resort to teacher-less classrooms where the educator is no longer there in person. Instead, students watch a live-streamed lesson on a screen that is being taught by a teacher in another location.

While it is great that modern technology allows this to happen and screen-based learning is becoming more and more common, surely it is no substitute for a having a teacher physically present in the classroom?

The reality of America's teacher shortages is that they disproportionately affect lower income districts.  Education is the best way out of poverty but breaking that cycle becomes more difficult if the teacher is the one who is being marked absent.