i just saw someone who was confused bout what subjects to pick, check the science handbook online. Find the major you are interested in and then work backwards from 3rd year subs finding the prerequisites. its not too bad if you organise what you wanna do.
and also you need a minimum of i think 12cp of advanced units in 2nd year. thats also in the handbook. i was too lazy to do advanced units so i just changed to the normal stream hehe, also so i can learn mandarin
btw after 1st sem like 25-50% of the advanced math students drop out to do the normal stream math coz it was insanely hard, or so they claim, they could just be a tad lazy