Magnets are cool. They are also quite tricky to understand. To help with understanding Magnetism at GCSE level I think it’s good to view the following excellent video on YouTube from Veritasium & Minute Physics.
I made a worksheet which is a companion to the video. It will help you make notes to keep and help with revision. I like this video because it gives you an idea why iron can be magnetic as well as not magnetic and how a permanent magnet can induce magnetism in another ferromagnetic object.