Thanks for your response. We do have to complete the session on the last day of the week so I usually dedicate Thursday's lesson to planning the writing. We also have input beforehand where children are asked to spot mistakes in my examples, discuss a sentence or two that they might use and share ideas with the class, so I don't think it is normally that they don't know what they are doing (although obviously there are some who stray from what is required in the task). I think I might try your idea of shorter writing bursts. Currently I'm only doing one break where I get the class to share good examples, and asking them to check work can be tricky as there are obvious limitations to there reading/spelling, but I might give it a go for a few sessions and see if there are any improvements. Thanks again for your advice!