there are three main differences: the content, the problems, and the IAs I do physics and chemistry, but all my friends do biology. All three of the sciences require memorisation to some degree: even though my friends complain to me about how biology requires them to "memorise the seven things blood carries" or "the x differences between cis- and trans- fats", even in physics and chemistry about 10 marks (often more) in paper 2 will be definitions. Physics is difficult for most unless you have previous experience doing difficult physics. Biology and Chemistry SL however, are very easy in terms of content, and most classes can finish them by the end of first term year 12. In terms of the problems, physics has more difficult problems in the test. a great deal of the time, the equations or techniques needed to arrive at the correct answer are unclear, and require a lot of question experience to answer quickly (especially in paper 2). I wouldn't recommend physics unless you really needed it for a career in engineering. This is because if you don't understand a concept in physics, it is harder to track down on the internet. In chemistry and biology, there are MANY sites that have dot point summaries of the syllabus, and questions in chemistry are straightforward and mostly limited to ONE syllabus chapter. In the IAs, the main difference is that Biology (for a 6/6 in DCP) almost always requires inferential and descriptive statistics. Data collection and procession requires more work to get full marks in for biology than the other sciences. In physics, design is a difficult component because any hypothesis should be supported by mathematical predictions derived from known laws etc. My personal recommendation is chemistry: you can get a lot of free online help, and a lot of the content is easy to follow: it makes sense. I may be biased by the fact that my chemistry teacher was AMAZING, really one of the best teachers at my school. in a physics exam, you might come across a question that you do not understand, or can't think of how to solve. In biology, you might forget something and those are marks you can't get back. In Chemistry, the maths is rarely difficult and just doing practise questions will teach you what kind of answers you need to put. "Explain why..." questions in chemistry are very common, but are GOOD questions to answer because the answer follows logically: it's not out of your conceptual grasp, it's not something you have to memorise blindly. Whether or not your chemistry teacher is boring is irrelevant: what you need to find out is which teachers are the most reliable at marking internal assessment? if the teacher gives a kid 16 when they deserve 8 and that gets sampled, that is a ridiculously high risk. It's happened to people i know, and so to stop this we all marked each other's IAs and got them remarked by another teacher if we thought the mark was too high. You can always do another experiment, but even if you get 18 and 18, being moderated down even 5 can be cripplingwhich teachers leave less holes in the syllabus? talk to old students. Even if the teacher can give an enthusiastic and engaging lesson, do they actually cover everything in the syllabus? i had teachers that taught us less than 1/3 of the syllabus: we were just expected to do the rest ourselves. This is NOT where you want to be. as boring and cheap as it sounds, you want a teacher who will spoon feed you content. this is easy marks, this is less research for you.which teachers get the 7s? you can ask this directly to them. ask previous years which kids got 7s they probably weren't smart enough to get by themselves, and which kids got 6s when they should have got 7. this is an important indicator of a teacher's ability.if you want an SL science and less work, i would say go chem or bio.