Parents have higher expectations of teachers, and students today can be more challenging to handle, said educators.
A 48-year-old primary school teacher, who joined the service in 1995, said parents in the past used to have more trust in teachers.
"Now, they will check assignments from school, check if you marked their kids' work correctly, or even compare the number of assignments you give compared to other classes or schools."
Some unreasonable parents even write to principals to complain about teachers, she added.
A former primary school teacher who left the Ministry of Education in August said: "Parents these days are more concerned about what their children are doing and learning in school... These are valid concerns, but it can create more work for us."
The 51-year-old, who joined teaching 18 years ago, added: "Many pupils have tuition, and sometimes they come with their school assignments and challenge you with different methods from their tutors."
There are also greater demands over the safety of students, said a 40-year-old head of department in a secondary school. He said: "The safety expectations today are far more cautious than when I first started teaching 15 years ago, especially for adventure activities. This indirectly results in increased demands on teachers' time.
"For example, in the past, one teacher could take out a class of 40 students. Today the ratio is about one teacher to 20, and if the activity is more intense, it is one to 10. But that is the current reality of parental and societal expectations, and we can't change that," he added.