A third of our students are in this position and most of them had decided they were bad at the subject. They were not.
The sentence I hear most often from a new A level student is that they are bad at chemistry. When I ask what they were taught in grade ten, it turns out that the honest answer is not very much, by somebody who had not studied it, and often not by the same person twice.
That is not being bad at chemistry. That is never having been taught chemistry. The two feel identical from the inside and they need completely different responses, so the first thing worth doing is telling them apart.
The test I use is simple. I ask a student to explain something from two years earlier that everything else stands on. In chemistry it is bonding and moles. In physics it is rearranging a formula and units. In maths it is fractions and negative numbers. A student who was taught it and found it hard will remember being confused by it. A student who was never taught it will have no memory of it at all, and will often say so with some surprise.
If you are in the second group, here is what actually works, in this order.
Go back before you go forward, and accept that it will feel like a step down. The first two months of a serious catch up are spent on material two years behind your grade, and it is the fastest route to your own syllabus rather than a detour. Every student who has refused this has taken longer.
Use recordings organised by topic rather than a course organised by date. Your problem is not this term. You need to be able to reach the lesson on the specific thing you do not know, watch it twice, and then move on. That is what a library is for and it is why ours is not locked by grade.
Get work marked by a person, early and often. This is the part students studying without a local teacher underestimate most, because with nobody around you there is no way of knowing whether what you are producing is any good. You can watch forty lessons and feel that you understand and write an answer that would earn two marks out of seven. Only a marked script tells you.
Write while you watch. A lesson watched with nothing in your hand is entertainment. Pause at every worked example, do it yourself first, then watch.
And ask about a reduced place if the money is the obstacle. Islands with no specialist teacher in a subject are exactly who our reduced places exist for, and the conversation is with the office and stays there.
One last thing to the students who have been told, or have concluded, that a science is not for them because their school could not teach it. You are drawing a conclusion about yourself from a fact about your island. They are not the same fact.