Writing difficulties come in all shapes and sizes. Basically children learn to write to having lots of practice, and being encourage to write and write. With one to one teaching the problems children have can be analysed and fed into the work without overloading the child with everything they are doing wrong at once.
My experience is that children enjoy writing if they don't feel threatened, and if the things they are asked to write about are fun and interesting.
My teaching emphasises encouragement but you wouldn't take this to mean that 'anything goes'. By no means. Encouragement is simply the best strategy to get the children writing.
Some children have problems with spelling, others with 'what to say', others with punctuation. These will all get picked up in the course of their practice writing, and will be sorted out. Over emphasis on errors, and the mixture of worry and impatience which some parents to feel about their own children's writing, can be very unproductive. And it comes about often by their being 'too close' to be a cool enough teacher
PRIMARY SUBJECTS HOME