Secondary school teachers do not need to be particular skilled in the arts of science or technology, they just need a basic understanding.
The government is now trying to hoard in as many teachers as possible, as cheaply as possible. My mum was a primary teacher. My sister has just qualified. I am stunned my sister will be teaching people, as she struggles with multiplication, division, the times table and turning a computer on, can't spell for **** and can't paint or draw, or play an instrument.
My ICT teacher once had to ask us how to turn her laptop on.
Wait until you get to university. There is a gigantic leap in the level of enthusiasm and knowledge. You'll be being taught by people who spend every hour they're not talking to you, reading about science.
Particularly with science, one person is never going to know all of it, if even some of it. So you'll still find lecturers at uni who have no idea about physics, but can go into the minute details of metabolic cycles and such.
The key is, team work. Sharing information and realizing when it's better to ask a physicist, chemist, electronics or maths guy. That really does have an impact that is so great, people are still trying to make full use of it via things like google data mining.
Most university level science now isn't chemistry, physics or biology, the labs will have a bunch of different people mixed in to maximize the skill sharing.