It might have been decades since you were last in a classroom, but most of us never forget the teachers who shaped our school days (for better or for worse).
Now - in a climate of increasing cuts and pressure on teaching staff to meet examination targets - former pupils from across the UK have decided to shine a positive light on education.
Simply by sharing a short message of gratitude for Teacher Appreciation Day.
Whether it is the person who taught their favourite subject, or someone who made them look at the world through new eyes, these teachers really struck a chord.
And helped make them the people they are today.
Someone pass us the tissues.