Epilepsy Action has produced an excellent booklet "Memory and epilepsy", written by a Professor at the University of Liverpool, because people with epilepsy may well have poor memory too. While the epilepsy part is irrelevant to you and DD, most of the booklet is about memory - explaining the different parts of it, and strategies to deal with it.
Hopefully, the ed psy assessment did assessments on the different parts of DD's memory? There is episodic memory, such as relating what happened during the day; semantic memory is for knowledge and facts; and procedural memory for activities like riding a bike, which we carry out almost without thinking. Memory can also be divided into verbal (what we hear) and visual memory (what we see). It could be that DD's difficulties with relating events could just arise from poor working memory, but she could also have poor episodic memory; or poor verbal and/or visual memory too?
Then there are three stages to memory:
- encoding - recording the memory
- storage
- retrieval - bringing information from long term memory to short term or working memory for use here and now.
The process can break down at any of those three stages.
As for maths, having to retrieve mathematical techniques from long term memory may be difficult for her. DD1 has profound memory problems, and the ed psy recommended that tasks for her rely on recognition, not retrieval from memory. For example, she should have had a filofax where the mathematical techniques such as addition and subtraction were laid out for her in examples; she only had to look at them and try to do the same with the task in front of her in that lesson, rather than being expected to try to remember how to addition or subtraction first each time. Same goes for times tables, expecting her to learn them is going to be a waste of time - just give her them in writing to refer to and apply in class. They could also write new words in a filofax, like scientific jargon, which she is likely to struggle to remember at first.
Attention is closely related to working memory, iirc from psychology lectures, so it could be that if DD has poor working memory, she has poor attention too - hence the difficulty in sticking to a task. Did the ed psy observe DD in class?
DD1 had other problems and a statement/EHC plan anyway, but she got 1:1 support in class (on top of a high staff to pupil ratio in small classes in a specialist school), because of her memory problems.