Firstly, let me say, I am glad that levels are going. I feel that it is a step towards getting pupils to be good mathematicians, rather than trained monkeys we get to jump through hoops to get certain grades(we can save that for Key Stage 4 and the new GCSEs).
The only issues I have are with consistency. I am happy that we could come up with a solution to our needs as a maths department, but would it be suitable for communication to parents, comparison with other subjects, comparison with other schools, progress since primary school etc.
My idea is for a system based upon pupils knowledge on certain topics, and that pupils have 4 levels of knowledge.
0. A lack of knowledge and an inability to grasp a mathematical skill.
1. An ability to perform a mathematical skill accurately.
2. An ability to apply a mathematical skill to solve problems and link to prior knowledge.
3. An understanding of why a mathematical skill would be applied and the inter-related nature of topics.
Below is an example of how it could work as an assessment sheet.
If pupils complete the sheet and it is marked, they should have a clear idea of their level of knowledge. At this point, they could fill in a grid, or potentially a survey online created using a form on google drive, so that you and the pupil both have a record of their ability levels on different topics.
In terms of reporting to parents, and consistency across subjects, would percentages of each of the 4 categories above work? Could you split up topics in English and assess whether pupils can use a technique, link techniques, or explain why techniques are used?