As a head of Science when looking through applications there are three key things I'm looking for. 1) That you have a passion for teaching and that you enjoying the role and being in the classroom and are committed to getting the best out of your students. 2) That you want to work in my department, at my school. That yo've done a bit of homework and talk about something that you've noticed. I dont want it to feel like you've put in lots of applications and that this is just another one. 3) That you understand the rigours of the job. That you talk about some of the key aspects of the role of a teacher, but also about those areas you would like to continue to develop. Hope that helps and good luck. As someone who is struggling to recruit at the moment maybe try and look further a field. The right job is out there for you.