I had in my class last year a 7 year old child who was FANTASTIC at science. Curious, orderly, fair, careful in his testing, always wanting to know the reasons for the things that he very closely observed ('when spiders walk, do they move each leg in turn like we do, or do they move one side then the other?' was one of his, as was 'what makes a magnet megnetic?', and 'what is it that lights up the sun?), patient, used precise scientific vacabulary etc etc.
He could not reliably count past 10 (though he could measure, and did so successfully, by observing and copying numbers from rulers / weights etc when needed for science), can read only CVC words (e.g. cat) and his writing is a string of mainly initial sounds.
I recorded his verbal answers to questions on a digital microphone, because it was important to me in science that his true ability as a scientist was recognised and we had evidence for it. Had I chosen to make him write his answers, and corrected every word, what would that have achieved? He already had 6 hours of Literacy lessons a week, plus a further 2 or 3 hours of interventions based on improving his basic Literacy and Maths. Why should I, in Science, emphasise the things he fails at yet again, rather than providing him with a way of showing, for that one hour, what he CAN do?