Issues raised included the need to spend time ensuring students understood the concept of 'delta x' (sorry, can't find how to put Greek letters into this post!), and the need for discussion about limits. Links were made to deriving the formula for the area of a circle by cutting it into sectors and rearranging to form a 'parallelogram', and discussing what we actually mean by recurring decimals (ie as the limit of a sequence). We all felt that focussing on the concept of limits was time well spent, as it underpinned so much of calculus.
In the discussion on differentiating trig functions I remembered a video we showed at Coffee and Pi about deriving the small angle formuale - can anyone locate a link for it please?
My original notes attached plus a simple spreadsheet.