I got into JMSS last year but didn't accept my spot. I did not find the tests very hard - it was really just the basics of science for year 9 and maybe some basic concepts of maths for year 10. there are 5 tests, 3 multiple choice and 2 written responses. when I looked at study guides and such for how to prepare I found it very overwhelming as there was so much I did not know however the test was mainly basic concepts or common sense. one note is that if you are doing accelerated maths make sure you revisit year 9 math concepts because I had forgotten a lot of it and I was really slow. There are two written pieces, one where you got diagrams and pictures and had to write a paragraph about that topic. for example, mine was about koalas and chlamydia and the impacts of that on their ecosystem. the second was we got the results of an experiment and we had to write a discussion on it, so just make sure you know the basics of a prac report. Hope this helps!