@TeenTimesTwo I also find that the lack of working out space on maths papers inhibits thinking. Does anyone else find that too?
This is often a problem when A4 past papers have been photocopied to A5 size to cut costs: there is then much less space than there should be. I drill everyone I teach about using lots of space, writing on any diagrams provided, and starting on the left: many teenagers seem to have a habit of starting their working in the middle of each line, wasting space. Also many pupils draw impossibly tiny diagrams: boys doing A-level maths seem to be the worst for this.
Some worksheets provided by schools have nowhere near enough space to show working, and pupils don't want to use separate paper as they should.
And worst of all are the maths websites which schools often use to set homework where you have to type your answer in, and writing out working doesn't seem to be encouraged at all.
One kind of question loathed by pupils are the long problem-solving ones: e.g. "here is an oddly-shaped floor, which needs polishing. One tin of polish covers 7.8 square metres, and each tin costs £8.99. How much will it cost to polish the floor?" Many pupils struggle with working out how to solve this. For this kind of question, I always tell pupils to write words in their working, e.g. "Area of floor". This is for their own benefit, because it's surprisingly easy to forget why you worked something out.
I also say regularly "mental arithmetic does not get you Brownie points: if it takes you more than five seconds, use a calculator, or paper as appropriate." The ones who are good at mental arithmetic often lose marks because they don't write things down.