Whilst I can see the point she's making, your tutor is a bit blunt to just throw that at you. Whatever your peers say about dropping doesn't mean anything anymore at this point.
When I was young, I was taught a lesson. Math is building a brick wall. If in one layer you don't place a brick, you can't safely build over it and expect it to be sturdy. If you lack a foundation, you can't build on top of that foundation and create development.
Unless, of course, you fill that gap with another brick. i.e., get back the foundation.
When it comes to lost marks, the main thing to ask yourself first is why are they being lost. Is it a result of stress, time management, content or whatever. That dictates the type of advice that'd be helpful to you. And the sooner you fix it all up, the more chances you have at acquiring that E4.
Since you have already singled out geometry, I'll give some advice regarding that first. You should still think about if anything else is impeding your results. If nothing else is, that's fair enough, but you should be thinking as hard as you can.
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For both 3U and 4U circle geometry, you can't expect to do it without the foundation - 2U geometry. If you cannot handle those questions, you need to backtrack and do them first. For 2U geometry, this is my checklist:
- Ensure that I know all the terminology first (e.g. notation, what an angle is and blah). This is of course easy.
- Categorise the main theorems. Some of the common ones include parallel lines, properties/tests for a quadrilateral, congruency and similarity
- Identify what makes each theorem characteristic. (e.g. alternate angles will feature the Z shape)
- Know what each theorem even looks like. (e.g. alternate angles are as above. Similar triangles are just one being larger than the other.)
- Start properly memorising each theorem. In doing so, you should be thinking a bit about HOW/WHY each thing happens. (e.g. "HOW" parallelograms have opposite angles equal to each other.)
- Optionally, start sticking theorems up on posters in your walls.
Then, you'd be tackling questions
- Recall what each theorem looks like.
- Single out EVERY bit of information in the question. In math, they will not give you extraneous data, unlike science which tries to trick you. And read the question to know what's important
- Draw a diagram if it's not already provided.
- Look at ONE TO THREE things at a time. Do not stare at the entire diagram. Focus on little bits of it, and move on when you can't draw the link quite yet.
- ANTICIPATE the possibility that the method is not obvious (especially in later parts of the question). Some questions may only be done BY first recognising similar triangles or a hidden quadrilateral. Never rule out possibilities, because only at most 20% of the time will an idea be stupid.
And you should be doing as many of these until you feel confident with it. Once you feel confident at all of that, KEEP those dot points and add in the following, as you start tackling 3U circle geometry.
- Terminology, once more. Especially things such as equal radii, concentric circles, concyclic points etc.
- Move through the theorems section by section. Ensure you know all the theorems involving chords and arcs, before adding in a cyclic quadrilateral. And lastly the tangents
- Again, recognise what each theorem LOOKS LIKE. (e.g. alternate segment theorem involves a triangle and a tangent. Memorise that, and which angles are equal. Another could just be angles in the same segment - the shape of the two triangles involved looks like a bowtie.)
- Make sure you know all of them. Textbooks such as maths in focus will leave out valuable ones. The Cambridge textbook has the lot.
- Once you know what they look like, draw them out again, labelling which angles are equal and at the very least think about why they are (i.e. the statement of the theorem itself)
Then, you'd be tackling questions
- There is more information that can be SUBTLY given, instead of made explicit. (e.g. if they tell you there is a diameter, then it's very much possible that the angle in a semicircle will be useful.)
- Put both 2U AND 3U theorems to the test. It's fair enough to prioritise 3U theorems, but that doesn't mean 2U ones are a waste. Especially once you get to 4U circle geometry - trick questions love to put in 2U theorems.
- Label angles everywhere. You never know where just working backwards on the diagram would help you. Nor do you always know that a pair of similar triangles have been hidden around.
It's important to work at a steady pace. You don't want to spend forever on it because it'll eat away valuable studying time for other things, but you DO want to spend enough time to get through each step properly.