At his stage during his N5 ds needed lots of support. Schools are focussed on teaching the content and don't spend a lot of time on revision and exam techniques. I would encourage any parent, even if you don't know the subject, to get really involved in the revision in N5 year. If they learn the techniques for N5 they will be much better prepared to do the more important Highers next year.
Past papers are brilliant for revision for final exams but difficult for prelims when the full course has not been taught yet. When ds started doing past papers he would get low marks too, I got him into the mindset that doing past papers was there to identify gaps and not to beat himself up about what he couldn't fully recall yet. I would sit with him after he did the paper and go through the marking instructions and we would make a list for every question and the marks lost
- missed units
- didnt label axis
- didnt answer actual question that was asked
- need to revise x
- need to practise calculation y
- and our favourite......I knew that but was a muppet
You tube was brilliant for chemistry, physics and maths, and we would pause the video if he started to click on what the answer was and he would finish it himself. Told him not to worry if marks were low, doing the past paper was a success as it gave him a list of gaps to work on for the next past paper and to only worry if he didn't keep (mostly) improving with each paper. Before doing the next paper he would remind himself to watch out for units/labels/check actual question was answered.
I know many of people say you need to leave them to it, but for N5 some kids do need lots of support to focus rather than waste time floundering. I knew nothing about the subjects but spent hours with ds (saved me paying a tutor!) marking papers, discussing techniques, finding resources and motivating him during N5, paid off when he got to Highers and I didn't need to get involved at all.
These sites are great for maths and physics past papers by topic
https://www.national5maths.co.uk/free-national-5-maths-2/
https://mrsphysics.co.uk/n5/wp-content/uploads/2022/11/N5PastPapers.pdf
some older chemistry past papers here
https://revisionscience.com/gcse-revision/chemistry/chemistry-gcse-past-papers/sqa-national-5-chemistry-past-papers
I think the courses changed slightly in 2018, but, I think I have 2014 onwards N5 past papers for english, french, physics, maths, modern, chemistry and 2016 onwards for Geography, saved somewhere if anyone needs any years for more practise and cant find elsewhere online - think most of the maths, physics and chemistry ones will be on the links above.