GCSE Maths

i'm doing GCSE Math Higher Tier and my teacher taught us differentiation, when i search online it only giving me A-level.
am i suppose to know about it or not.

Well I do higher tier edexcel and as far as I remember it is linked to the graphs. I think any further may be for gcse further maths or a level. To be sure check your examboard's specification. That should confirm whether you need to know differentiation or not.