I am not sure how to put this in IEPs. My DS struggled with understanding why he had to show steps because he does math intuitively and in his mind and really did not know how or why to show his work. He is in a school that is very picky about showing work (for 2nd grade) that he lost 15 to 20 points in math on weekly tests even when he got it all correct. Both the teachers and we coached him for a few weeks. For him, pictorial representations worked better than writing long winded explanations of the type "x happened because of y ..." . So, we taught him the SM bar diagram models, number line depictions, pictorial depictions (boxes with grouped pictures to represent multiplication/division, pictures of clocks for time problems, stick people nicely labeled and ordered for problems with ordering/logic etc) and sat with him to do his homework with him for 2 weeks and tutored him as to what exactly was needed.
After those 2 weeks, we told him that if he could show his work satisfactorily, he was free to move on to other stuff of his choice. But, if the "showing work" part was unclear, he needed to do an extra word problem and show work again. This turned out to be the best strategy for us - he figured that he could do less problems if he could show work effectively and ever since, showing work is not an issue.
