Highly effective teachers can affect students for years to come and have a direct impact on what we earn. Are we giving credit where it's due?

Teachers have a thankless task for the most part, filling in the gap created between inadequate systems, broken budgets and careless parenting.

And their reward for their troubles? At worst, harassment and even violence and, at best, cursorily scribbled Christmas cards in December and battered chocolate eggs at Easter.

Yet, as we grow older, the importance teachers have had on our lives often starts to become clearer.

Although, when I was at school, Mrs Theasby may have put me off Physics for life with her stern approach to teaching, Miss Mulvihill introduced me to, and shared with me, her love for English literature, while my enthusiastic young French teachers inspired me to study languages all the way to university and beyond.

Miss Brownlow, the aged and hesitant Maths supply teacher, taught me about the impact of body language – her panic at a simple ruler being tapped on the desk by an impatient student was an intriguing lesson in how seemingly innocent gestures can inspire terror in the elderly.

Miss O'Shea's constant admonition of our class for unruly behaviour, while also commending us for raising the most funds for charity, demonstrated how you could hate the sin and love the sinner – a pretty relevant lesson for a Catholic school.

Even Miss Bondi, our Spanish teacher who spent more time out of school than in it, taught me a valuable lesson; that when there's no teacher around, you'd better be motivated enough to teach yourself. Managing an ‘A' grade in Spanish through my almost self-taught efforts gave me a morale boost that has since been hard to match.

My schooldays are far behind me yet these are among many memories that will stay with me for years to come. And I am not alone in developing a belated appreciation for those who were charged with educating me.

A recent survey in the United States by ING Foundation looked at the impact that teachers have on our lives and found that while the vast majority of respondents (88%) felt they had a teacher who had made a ‘significant, positive impact' on their lives, teachers received less gratitude than other ‘helping professionals' such as social workers, nurses, clergy or doctors.

98% of Americans surveyed believe that a good teacher can change the course of a student's life and that, outside of family, teachers have the greatest impact on our lives growing up, even more so than friends. Almost everyone (94%) agreed that we need to do more to recognise our good teachers.

Appreciation is often belated, however, with 87% of those surveyed admitting that they wished they had told their best teachers how much they appreciated their efforts.

Teachers play a critical role in preparing our young for the challenges they will face as adults and recognising and rewarding this role is the sign of a responsible society.

The legacy of a good teacher can even, it seems, be traced back to our earliest days in school. A study by Raj Chetty, a Harvard economist, found that students who had learned much more in kindergarten were more likely to go to college than students with otherwise similar backgrounds. Students who learned more were also less likely to become single parents. As adults, they were more likely to be saving for retirement and, perhaps the most striking finding, they were earning more.

The crucial problem the study set out to solve was that of causation-correlation. Are children who do well in kindergarten tests destined to do better in life, based on who they are? Or are their teacher and classmates changing them?

Mr. Chetty and five other researchers examined the life paths of almost 12,000 children who had been part of a well-known education experiment in Tennessee in the 1980s. The children who are now about 30 are well into their adult lives.

With all else equal, they were making about an extra $100 a year at age 27 for every percentile they had moved up the test-score distribution over the course of kindergarten. A student who went from average to the 60th percentile — a typical jump for a 5-year-old with a good teacher — could expect to make about $1,000 more a year at age 27 than a student who remained at the average. Over time, the effect seems to grow, too.

While factors such as the class size played some role - classes with 13 to 17 students did better than classes with 22 to 25 – and peers seemed to matter, none of these factors came close to explaining the variation in class performance, leaving only one plausible explanation: the teachers.

Highly effective teachers, the study showed, can affect students for years to come. Mr. Chetty and his study team estimate that a superb kindergarten teacher is worth about $320,000 a year – the amount of additional money a full class of students can expect to earn over their careers. And this estimate doesn't even take into account other social gains, like better health and less crime.

Even if we can't directly influence government policy on pay and working conditions for teachers, we can influence how we treat the teachers we – and our children – come into contact with.

As any parent will attest, it is often hard to recognise the description of your child when speaking to their teacher. A child who has to be nagged to pick up their toys at home is transformed into teacher's most helpful pupil at school. The little girl who barely stops talking long enough to draw breath when you pick her up from school is praised for being focused and not chattering in class.

While we are happy (and sometimes stunned) enough to accept these accolades, we should also be ready to accept the less than perfect observations about our children's behaviour, attitude and performance in school.

Supporting a teacher's decision or questioning it in a positive manner, rather than challenging it, will not only show our children that teachers deserve respect, but will help teachers work with us in a positive way to support a child – ensuring that everyone wins.

And while a good teacher can change the course of a person's life, we also need to remember that even the best teacher may not be able to save a child when parents fail to do their part. When a child is led astray, our first rush to judgement shouldn't be to blame their teachers but to question our own effectiveness in leading our young people down the right path and in building the confidence they need to avoid making poor choices. Because it is only when we, as parents, guardians, carers and family, play our part in moulding the characters of our children, that teachers have a clear stage on which to play theirs.

And few can deny that most teachers do a remarkable job in building on the raw, noisy products we send to them almost every week day of the year.

Among the vast majority of Americans in the ING study who said they had a teacher or teachers who had a "significant, positive impact" on their life growing up, 83% said they had a teacher who helped build their confidence and self-esteem, 79% had a teacher who encouraged them to pursue their dreams, 75% said a teacher served as a mentor or role model, and 54% said that a teacher helped them through a tough time.

Better late than never when it comes to recognition, it seems, as in later life our teachers are eventually admired and appreciated – an overwhelming 93% of those surveyed agreed that teaching is a noble profession, while 89% believe teachers have a "really hard job."

Good teachers are unsung heroes who rarely get to see the long-term fruits of their labours. So this Christmas I'm making sure that my kids' teachers receive not just a card with a scribbled signature, but a message that says thank you today for what we are learning for tomorrow.

It's never too late to say thanks for the lessons that lasted a lifetime. I'm with the 87% that wish I'd said it then but, if I can't thank Miss Mulvihill directly today, I can at least show some appreciation for her legacy.