Previous posters have already given you some good advice and the main point that resonates with me about their advice is to keep taking photos.
Take lots of photos (I mean lots), edit them down by categorising them into commonalities; People, women, men, places, trees, mundane objects, fast things, red things, black and white things, blurry things, close ups, macro shots, vibrant colours, landscapes, portraits, broken things, fixed things, wet things etc.
Print out a contact sheet of your categorised photos and write about them in your art book. Always write about what you've done. Even if your teacher doesn't think the photos have a theme or conceptual meaning that brings them together at least you can show him that you are looking.
Consider how cropping your photos can change their meaning, changing the colour or converting them to black and white.
Conceptual meanings you could pursue:
1. Collections: the idea of documenting a collection of things, or collecting things that are the same or similar.
What does 50 photos of similar objects mean?
2. Portraits: Set up a space to take photos and talk to your sitters (fellow students) while you are taking their photos. The goal here is to capture a particular moment when people are vulnerable, a slice of life, a split second. Ask the sitter "What are you going to do when they finish the HSC?". You have a split second opportunity to capture the moment of fear, apprehension, hope, joy
3. The Unseen: Capture the beauty in something that people discard or walk over or dismiss.
4. Set up something odd/interesting/out-of-place and photograph the reaction of randoms as the pass by.
5. 50 photos of the same thing. What happens if you construct a single image out of 50 polaroids? Print out and layer the photos over the top of each other to construct a single image. It reminds me of scales, or moments in time, fragmentations of an idea, piecing together identity.
PS, I would recommend against flipping off your teacher. Despite him frustrating you he is trying to guide your artmaking.
Good luck.
Feel free to ask any questions.