I haven’t always been a teacher. I used to work in an office. My day started at 9am after an unpleasant commute. For the next 30 minutes, my colleagues and I would respectfully ignore each other while kettles were boiled and computers turned on.

The ice would usually begin to thaw by 9.30am, but it wasn’t uncommon for me to sit at my computer without speaking for up to an hour. And that was OK. That was the code we had all subconsciously signed up for.

But teenagers do not understand this code. The teaching day does not warm up and thaw out in a slow and civilised manner. The ice shatters unceremoniously, whether you’re ready or not, as soon as you step through the front door.

So you have to be prepared. If you believe that your teaching persona can begin and end at the classroom door, then you must expect your behaviour management to suffer. To gain the respect of students and ensure that they adhere to your rules, you need to constantly reinforce your authority outside your domain. I call it Teacher Mode and wherever you are in a school, at whatever time, you need to be in this zone.

It is not always easy, but I have come to appreciate that the better I get at slipping into Teacher Mode outside the classroom, the easier I find it within my classroom, so the effort proves worthwhile. Here are a few things that can make Teacher Mode a little easier to maintain.

Knowing me, knowing you

I try to invest time at the beginning of the academic year learning as many students’ names as possible. It is hard because there are so many of them to remember but it really is worthwhile. People like acknowledgement, whatever their age. If you show them that you know who they are and that you can single them out among the crowd of 1,300, they will be much more likely to respond positively when they arrive for your lesson.

Play the game

I am ambivalent about some aspects of school policy. However, as a teacher, you have to accept that school is a world of “us” (the teachers) and “them” (the students), and that teachers have to present a united front. Therefore, when walking around the school corridors, be the teacher who challenges: pick up litter (or, better still, get a child to do it), ask students to tidy their appearance, tackle the 16-year-olds “befriending” kids five years their junior, make students hold the door open and get out of the way for the canteen staff when they are pushing huge trolleys full of food, always move on pupils who have become embroiled in public displays of affection. If you show them that you are 100 per cent focused in the corridors, they will know that you are someone who means business in the classroom.

Get involved

Life as a teacher never stops. However, the most rewarding experiences for me are often the most unexpected: a detour via the library to take part in a lunchtime quiz, running a club or arranging a school trip. Some of my best moments as a teacher have been outside the classroom. These have varied from visiting other countries to taking students to the theatre. I can’t remember much from my own education but I am pretty sure I could recount every trip I ever took part in and every teacher who went on them. For me, those were the moments to remember. The paperwork involved can be annoying but the outcomes are always worthwhile. If you become known as “the teacher who took us to.”, the students will want to please you so that you take them somewhere fun, too.

It’s good to talk

When I was a newly qualified teacher, I mastered the art of phoning home as a way of managing bad behaviour issues and I still advocate it as a useful method. However, I have also learned the power of the positive phone call. Hearing the switch between “What have they done now?” to “Wow.really?” is a great feeling. It reminds me why I signed up for teaching. The knock-on effect in your classroom can be amazing, too. Work ethic and behaviour often magically improve once parents hear good things.

I enjoyed working in an office and, at the time, I couldn’t have imagined starting the working day in the way I do now. It would have seemed unimaginably uncivilised. I am the first to admit that being in Teacher Mode from 7.45am until anything up to 7pm is utterly exhausting. However, six periods of managing unruly behaviour in the classroom is much more tiring, so switching into Teacher Mode as you walk in the door is definitely worth it for the benefits that it will bring.

Katie White is an English teacher at Kingsbridge Community College in Devon

What else?

How much should teaching dictate your personal life?

Check out this Teachers TV video on developing a professional persona.