Once you have used Write & Improve you will realise that it is not a grammar and spelling checker which sometimes returns random results. It does not mark up every error, and it does not self-correct your work. These reflect two key principles behind the tool.
Write & Improve’s approach to error identification and correction is two-fold. It is designed not to give too much ‘red pen’ feedback in one go as this can be ultimately demotivating and counter-productive. It incrementally supports the learner as they review and resubmit their work to improve their writing.
It returns feedback on common errors, where there is a very high level of confidence in the diagnosis. It cannot identify every error, although more and more errors are being detected and added to the engine.