A newly qualified teacher once said, "On my course we were told not to bother taking portfolios as they're not considered important, but I'm sure that I got my job on the strength of mine - no one else had one."
Carrying a portfolio, whether the interviewing panel looks at it or not, will give you that all-important injection of confidence. Like feeling right in the clothes you wear, it will give you the extra inch that means you get the job rather than being a frustrating close second. But you don't have to have one and some people advise against them.
It takes time to create a good portfolio, but it's worth it. One of the problems people face is that the label "portfolio" is used to describe considerably different objects that have completely different purposes.
Some portfolios are intended for a certain audience and others are intensely private; some are kept for a certain time and others are career-long.
There are the lever-arch folders in which people collate evidence against standards - for higher level teaching assistants, qualified teacher status, threshold or advanced skills teacher status. Professional development portfolios contain a record of teachers' training and development, objectives, action plans, and lesson observation feedback.
Some portfolios are tools for reflection, containing learning journals or reflective diaries. Others are for putting all information relating to you as a teacher: job descriptions, qualifications, performance management, letters from grateful parents and pupils.
Some people, especially primary teachers, go for the kitchen sink approach: in with qualification certificates, CV, and a mixture of lesson plans - mainly literacy and numeracy, but also science, history and so on to show planning skills across the curriculum - and photos.
From the interviewers' perspective, they don't have long to interview you and they won't want to spend time leafing through a big folder. Choose one lesson or project that is illustrative of your best - for variety, ideally not the same one you used in your application.
The plan should be detailed to hit all the right notes (clear learning objective, assessment criteria, individual education plans, deployment of assistants, and so on); examples of resources; photos; a range of work that came out of it that's marked in an exemplary fashion; and an evaluation of the learning, your teaching and next steps.
Go for quality not quantity: limit it to 10 pieces. Make sure it's tip-top in terms of content and presentation so that it sends messages about your high standards, organisation, and literacy and ICT skills. The cover should look appealing so that people will want to open it - even if they don't have the time, they'll assume something stunning lies within. Make sure it's properly secured in a folder or ring binder.
Some interviews will give you a five or a 20-minute slot for presenting.
When you're planning remember to allocate time for questions. Most of the time you'll be left not knowing whether to thrust your portoflio in their faces or waiting to be asked. Don't keep it hidden. Have the confidence to draw on sections when you're answering questions.
Sara Bubb is The TES new teacher expert and answers queries on the website: www.tes.co.ukstaffroom